NOTABLE SCIENTISTS

A TO ZOF

SCIENTISTS IN SPACE AND ASTRONOMY

DEBORAH TODD AND JOSEPH A. ANGELO, JR.

A TO Z OF SCIENTISTS IN SPACE AND ASTRONOMY

Notable Scientists

Copyright © 2005 by Deborah Todd and Joseph A. Angelo, Jr.

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Todd, Deborah.A to Z of scientists in space and astronomy / Deborah Todd and Joseph A. Angelo, Jr.

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“I know nothing with any certainty, but the sight of stars makes me dream.”

—Vincent Van Gogh

“All of us are truly and literally a little bit of stardust.”

—William Fowler

To the loves on this very tiny planet who have sprinkled their stardust into my lifeand believed in my dreams.

To Jason, my original and brightest star.

To A from T.

To Rob, as always, with love.

To Jenny.

To Gregg, thank you for everything.

To Rusty, our beloved star.

To Mom and Dad.

To my Sister.

Out of stardust comes poetry . . .

To Jeb, for the music and art.

To Omar, my favorite poet of all time.

—Deborah Todd

To my special friend, Michael Joseph Hoffman, his brother, Daniel, and all the other wonderfulchildren of planet Earth who will inherit the stars. At just three years old, with the same

unquenchable curiosity that inspired so many of the interesting people in this book, Michaelasked me: “Where does the Sun go at night?” This book is written to help him discover anincredible universe that is now both a destination and a destiny through space technology.

—Joseph A. Angelo, Jr.

CONTENTS

List of Entries ixAcknowledgments xi

Introduction xiii

Entries A to Z 1

Entries by Field 286Entries by Country of Birth 289

Entries by Country of Major Scientific Activity 291Entries by Year of Birth 293

Chronology 295Bibliography 299

Index 305

ix

Adams, John CouchAdams, Walter SydneyAlfonso XAlfvén, Hannes Olof GöstaAlpher, Ralph AsherAlvarez, Luis WalterAmbartsumian, Viktor

AmazaspovichAnderson, Carl DavidÅngström, Anders JonasArago, Dominique-François-

JeanAratus of SoliArgelander, Friedrich Wilhelm

AugustAristarchus of SamosAristotleArrhenius, Svante AugustAryabhataBaade, Wilhelm Heinrich

WalterBarnard, Edward Emersonal-Battani Bayer, JohannesBeg, Muhammed Taragai

UlughBell Burnell, Susan JocelynBessel, Friedrich WilhelmBethe, Hans AlbrechtBode, Johann ElertBok, Bartholomeus Jan

Boltzmann, LudwigBradley, JamesBrahe, TychoBraun, Wernher Magnus vonBruno, GiordanoBunsen, Robert WilhelmBurbidge, Eleanor Margaret

PeacheyCampbell, William WallaceCannon, Annie JumpCassini, Giovanni DomenicoCavendish, HenryChandrasekhar,

SubrahmanyanCharlier, Carl Vilhelm LudvigClark, Alvan GrahamClausius, Rudolf Julius

EmmanuelCompton, Arthur HollyCopernicus, NicolasCurtis, Heber DoustDirac, Paul Adrien MauriceDoppler, Christian AndreasDouglass, Andrew EllicottDrake, Frank DonaldDraper, HenryDyson, Sir Frank WatsonEddington, Sir Arthur StanleyEhricke, Krafft ArnoldEinstein, AlbertEuler, Leonhard

Fleming, Williamina PatonStevens

Fowler, William AlfredFraunhofer, Joseph vonGalilei, GalileoGalle, Johann GottfriedGamow, GeorgeGiacconi, RiccardoGill, Sir DavidGoddard, Robert HutchingsHale, George ElleryHall, AsaphHalley, Sir EdmundHawking, Sir Stephen

WilliamHerschel, Caroline LucretiaHerschel, Sir John Frederick

WilliamHerschel, Sir WilliamHertz, Heinrich RudolfHertzsprung, EjnarHess, Victor FrancisHewish, AntonyHohmann, WalterHubble, Edwin PowellHuggins, Sir WilliamJeans, Sir James HopwoodJones, Sir Harold SpencerKant, ImmanuelKapteyn, Jacobus CorneliusKepler, Johannes

LIST OF ENTRIES

x A to Z of Scientists in Space and Astronomy

al-Khwarizmi, AbuKirchhoff, Gustav RobertKorolev, Sergei PavlovichKuiper, Gerard PeterLagrange, Comte Joseph-LouisLaplace, Pierre-Simon,

Marquis deLeavitt, Henrietta SwanLemaître, Abbé-Georges-

ÉdouardLeverrier, Urbain-Jean-JosephLippershey, HansLockyer, Sir Joseph NormanLowell, PercivalMessier, CharlesMichelson, Albert AbrahamNewcomb, SimonNewton, Sir IsaacOberth, Hermann Julius

Olbers, Heinrich WilhelmMatthäus

Oort, Jan HendrikPenzias, Arno AllenPiazzi, GiuseppePickering, Edward CharlesPlanck, Max KarlPlatoPtolemyReber, GroteRees, Sir Martin JohnRossi, Bruno BenedettoRussell, Henry NorrisRyle, Sir MartinSagan, Carl EdwardScheiner, ChristophSchiaparelli, Giovanni

VirginioSchmidt, Maarten

Schwabe, Samuel Heinrich

Schwarzschild, KarlSecchi, Pietro AngeloShapley, HarlowSitter, Willem deSlipher, Vesto MelvinSomerville, Mary FairfaxStefan, JosefTereshkova, ValentinaTombaugh, Clyde WilliamTsiolkovsky, Konstantin

EduardovichUrey, Harold ClaytonVan Allen, James AlfredWilson, Robert WoodrowWolf, MaximilianZwicky, Fritz

xi

The creation of the universe took a matter ofseconds. The creation of this book took

somewhat longer. These acknowledgments are tothank those wonderful people who helped de-velop it from its original flicker of light into theshining example of the completed collaborationthat it is today. First and foremost: to Chris VanBuren, who is now living the life of his dreams ina land far, far away, thank you for working usthrough the spark phase and into the realm of re-ality; to Margo Maley Hutchison for pickingthings up in the middle of it all with kindness andgrace; to Kimberly Valenti for taking it the finalmile—the hardest part of the journey—you aredeeply appreciated; and to Bill Gladstone for in-sisting that I meet your “first writer,” because weboth live in the same county—thank you for in-troducing me to someone who has surely becomea lifelong friend, and now part-time collaborator.

To Ed Addeo, a fabulous friend, and anequally wonderful writer. Your help was aboveand beyond the call of duty and/or friendship.You kept me afloat and made this book possible.And to think we did it all without being in thesame room, except of course for those occasionallunches that kept us going and kept me sane.Thank you, thank you, thank you.

To Rob Swigart for the use of your office,your house, your kitchen, your desk, your otherdesk in the library and that wonderful chair, andyour apartment in Paris. I’m still not sure about

ACKNOWLEDGMENTS

the change you made in my computer situation,but I guess honestly I am liking it more and moreevery day, and my computer and I have bothbeen virus free since the switch! I know—youtold me so. Thank you.

To Roger Eggleston for his great research, ata moment’s notice, with a smile. To ElizabethEggleston for always smiling and always believ-ing in this project and me. Thank you to bothof you for your always-present support. Who’s incharge? I know!

Special thanks to Kasey Arnold-Ince for herresearch skills, Heather Lindsay for her photoexpertise on both books, Gregg Kellogg for againdiscussing biography candidates with me and themultitude of offers to help, and Curtis Wong foralways asking how my book was coming alongand the many varied discussions we had on thistopic and others.

Thank you to John Newby, who continuesthe mantra “Keep moving forward.” I am gladyou were passing through. You are a collectionof very special stardust.

Thank you to Matt Beucler. You know why,coach.

A special thank you to the editorial staff atFacts On File, especially Frank Darmstadt, forpulling the project through and helping bring itto completion with patience and understandingthrough cancer, physical disabilities, and thepassing away of loved ones, and Laura Magzis,

xii A to Z of Scientists in Space and Astronomy

for an excellent copyediting job. To Joe Angelofor his expertise, dedication, and years of expe-rience in this book-writing process that provedinvaluable in getting it completed.

To my sister, Drena Large, I simply say“Thanks, Sis” for being the great listener andproblem solver that you are. You didn’t know it,but you helped tremendously.

Thank you to Jennifer Omholt. You proveto me daily that laughter is the best medicine.Thanks for listening and for the perspective.

My fondest thank you to Jeb Brady, for be-ing an amazing collection of stardust and forcontinuing to shine brilliantly. Thank you forintroducing me to the concept of “Life on PlanetZiploc.” You make me laugh. I love you.

Finally, thank you to my son, Jason Todd, thestar that forever shines brightest in my universe.

—Deborah Todd

This book could not have been prepared with-out the generous support and assistance of Ms.Heather Lindsay, curator of the Emilio SegrèVisual Archives (ESVA) of the AmericanInstitute of Physics (AIP). Special thanks also goto the staff at the Evans Library of Florida Tech,whose assistance in obtaining obscure referencematerials proved essential in the success of thisproject. Finally, a special thanks is extended tothe editorial team at Facts On File, particularlyexecutive editor Frank K. Darmstadt, who kepta steady hand at the wheel while the draftmanuscript traveled through uncharted, oftenturbulent, waters.

—Joseph A. Angelo, Jr.

xiii

The best thing about writing a book on theA to Z of Scientists in Space and Astronomy

is discovering that many of the most amazingcontributions were made by ordinary people wholoved gazing at the stars. Musicians, philoso-phers, priests, physicians, people who came fromimpoverished backgrounds, and those with un-told wealth, have all contributed to our under-standing of what we see when we look into thenight sky, and where we fit into the scheme ofthings. Astronomy, unlike any other field, canbe and has been significantly affected by ama-teurs. The stars are for everyone.

Throughout time, the stars have guided peo-ple in all walks of life in a variety of ways—tonavigate ships, determine when wars should bewaged, decide when marriages should take place(and to whom one should be married), wherebuildings should be erected, and when fieldsshould be planted and harvested. Astronomyand astrology were once a single discipline, andimportant aspects in medical care. Even today,the medical profession admits that emergencyrooms get a little crazy during full moons. Andof course there is the term lunatic, which comesfrom the Latin luna, “the Moon.”

Astronomy has allowed us to standardize ourclocks and our calendars, and has provided uswith some sense of order in our very busy lives.And as our bodies and internal clocks work intime with solar and lunar and stellar events, we

INTRODUCTION

cannot deny that we are all inexplicably con-nected to this tiny planet and to the place it oc-cupies in a vast space that we are still strivingto understand.

Our unquenchable thirst for knowledge inthe galaxy and the universe has propelled us intospace, traveling in search of answers. We havesent new kinds of ships into a new unexploredterritory, gathering samples and pictures fromplaces that are too far away for any human totravel, yet. And just in case, hoping that wemight not be alone, we beckon a response fromany other travelers who might be out there alsoexploring.

This book was written to introduce you tosome of the inspiring people who have dedicatedthemselves to this field and have made it possi-ble for us to learn more. Many have given theirlives to their studies, and far too many have losttheir lives for their beliefs. Some pursued find-ing answers in the stars as a hobby over a life-time. Others made great contributions during ashort period of time, and then left the field topursue other interests. Yet their commonality isone that we all share—the wonder of looking upat the night sky. At least once during your life-time, look through a telescope at the Moon, ora star, or a comet, or a planet. And when youdo, remember that even Galileo could not haveseen the wonders that you can see. It would havebeen beyond his wildest dreams.

xiv A to Z of Scientists in Space and Astronomy

ENTRIES

The entries in this book run the gamut from rel-atively unknown amateurs to the most highly re-garded scientists in astronomy, cosmology, andphysics. If there were more time and more space,there would be many, many more worthy peopleincluded in this book. Perhaps future editionswill have further additions.

Each entry here is arranged in alphabeticalorder by surname or, in the case of the ancients,by the name by which they are most commonlyknown (for example, Ptolemy). In the instancesof those whose names have had many differentspellings, a variety of spellings have also beenincluded. Following the name, you will find birthand death dates, nationality, and field of spe-cialization.

The biographies are typically 750 to 1,200words, usually containing some informationabout the subjects’ childhood and family back-ground, and exploring influences, progressioninto the field, educational background, and,

most important, work and contributions to thestudy of space and/or astronomy. Where there isa name listed in SMALL CAPS within the body ofthe biography, that name will be listed as its ownbiography within the book.

CROSS-REFERENCES AND BIBLIOGRAPHY

Following the alphabetical entries are a numberof cross-reference indexes. The Chronology listsentrants by the periods in which they lived. Theyare also grouped by birth dates in the Year of Birthsection, plus by Country of Birth, Scientific Field,and Country of Scientific Activity.

An extensive bibliography lists resourcesused in the research of this book, including bothprinted material and Web sites. As you whetyour appetite reading about these extraordinarypeople, you are invited to use these resources asa starting place to help you learn more about sci-entists in space and astronomy.

—Deborah Todd

A

1

5 Adams, John Couch(1819–1892)BritishAstronomer, Mathematician

John Couch Adams, a brilliant scientist oftendescribed as shy, reserved, and even self-effacing,is best known as a central figure in a scientificfiasco that sparked an international debate, pit-ted nations against one another, and brought theworld of astronomy out of academia and into thelife of the average citizen. Adams’s involvementin the missed discovery, and subsequent codis-covery, of the planet Neptune became one of themost important events in the history of astron-omy, from both a scientific and a political pointof view.

Born in 1819, the son of a farmer, Adamsreportedly showed great mathematical abilityfrom the time he was young, and at the age of16 calculated the time of an upcoming solareclipse. Four years later, in October 1839, Adamsbecame a student at St. John’s College inCambridge, a town that Adams stayed tied to forthe rest of his life.

Shortly after the discovery of Uranus by SIR

WILLIAM HERSCHEL, astronomers discovered abaffling problem with that planet’s orbit. Adams,in his second year of college, suspected that theproblem was another planet, writing in 1841

that “the irregularities of the motion of Uranus”had him questioning “whether they may be at-tributed to the action of an undiscovered planetbeyond it.” His studies, and later his work, keptAdams busy, but he planned on “investigating,as soon as possible after taking my degree” (an-other two years away), the possible explanationfor the planet’s orbit, believing that he wouldthen “if possible . . . determine the elements ofits orbit, etc. approximately, which would prob-ably lead to its discovery.”

Unfortunately, life got in the way, protocolgot in the way, and ineffective tools and peoplegot in the way. The chain of events that tookplace between Adams’s documented idea in July1841, in which he suspected the existence of an-other planet, to his computations of the planet’slocation, to the actual discovery of the planet inSeptember 1846, was a slow and painful pro-gression. The time span of more than 5 years al-lowed plenty of time for outside forces and peo-ple to complicate matters, and the result was afull-blown scandal. The idea that “he who pub-lishes first gets the credit,” which was the pro-tocol of the time, did not help Adams either.The professional positions and personal obliga-tions of the people involved further complicatedthe events that followed.

In 1841 Adams was a second-year studentconvinced that there was another planet beyond

2 Adams, John Couch

Uranus. He was overworked with his studies, butstill reportedly spent hours by candlelight, work-ing through the night on mathematical compu-tations to pinpoint the planet’s location. Whilethis was unknown to the rest of the world at thetime, Adams was the first person to use Newton’stheory of gravitation as a basis for calculating theposition of a planet.

Two years later, in 1843, Adams graduatedwith extraordinarily high marks from Cambridge,receiving the award of First Smith’s Prizemanand a fellowship at Pembroke College. He soonbecame a curator of the Cambridge Observatory,and his career was underway. In October he

completed computations for the location ofthe planet, and shared his theory with theAstronomer Royal, Sir George Airy. But Airydisagreed, and thought that the problems withthe orbit were related to the inverse square lawof gravitation, in which gravitation begins tobreak down over large distances. Airy’s dismissalof the computations, compounded by new teach-ing responsibilities, kept Adams from pursuinghis theory.

Despite the setbacks, Adams had a brilliantmind, and although he was not what anyonewould ever call aggressive, he was persistent aboutcalculating the planet’s position. Adams requestedadditional data on Uranus from Greenwich.Through the director of the Cambridge Observ-atory, Professor James Challis, Adams requestedadditional data from Airy in Greenwich, and inFebruary 1844, the information was sent.

DOMINIQUE-FRANÇOIS-JEAN ARAGO, thedirector of the Paris Observatory, was also in-terested in Uranus’s orbital problems, and healso thought another planet might be in-volved. In June 1845 he requested that one ofhis astronomers, URBAIN-JEAN-JOSEPH LE

VERRIER, work on the solution to find thisplanet. Arago did not know about Adams’swork, and Airy did not know that Arago waslooking for a planet.

By September Adams’s calculations werecomplete, and included the location of theplanet, its mass, and its orbit. Adams personallytook his findings to show Airy, but Airy wasaway in France, so Adams left a letter of intro-duction written on his behalf by Challis.Despite the fact that it was common for peoplefrom all walks of life to write to and drop in onthe Astronomer Royal, Adams’s behavior ofshowing up without an appointment is oftenhighly criticized and cited as a contributingfactor to the fiasco.

The following month, Airy wrote to Challissaying that he would see Adams, and Adamstraveled once again without an appointment to

The British astronomer John Couch Adams, who iscocredited with the mathematical discovery of theplanet Neptune in the 19th century. From 1843 to1845, he investigated irregularities in the orbit ofUranus and used mathematical physics to predictthe existence of a planet beyond. However, hiswork was ignored in the United Kingdom untilUrbain J. J. Leverrier made similar calculations thatallowed Johann Galle to discover Neptune onSeptember 23, 1846. (Courtesy of AIP Emilio SegrèVisual Archives)

Adams, John Couch 3

see the astronomer. When he arrived, Mrs. Airytold Adams that her husband was out, so he lefthis card saying that he would return later in theday. She forgot to give the card to Airy, and whenAdams returned as promised in the afternoon, hewas told that the family was having dinner, whichthey did every afternoon at 3:30, and he wasturned away again. Adams left his papers forAiry to review, and returned to Cambridge.

Airy still questioned Adams’s theory, evenafter looking at his calculations and explana-tions, and later wrote to him asking specificallywhether the new planet could explain some ofthe discrepancies of Uranus’s orbit. Many thinkthat Adams was bothered by the question be-cause he thought it was missing the point—hehad identified a planet and gave complete andthorough calculations. For whatever reason,Adams did not write back.

In November 1845 LeVerrier published a pa-per stating that Jupiter and Saturn definitely didnot cause Uranus’s orbit, insisting that anotherfactor had to be involved. On June 1, 1846, hepublished another paper, this time stating withcertainty that another planet beyond Uranuswas the only possible explanation for Uranus’sorbit. Airy got a copy of LeVerrier’s paper onJune 23, and wrote to him asking the same ques-tion he had asked Adams approximately sixmonths earlier. This put Airy in the possessionof information making him the only one whoknew that Adams and LeVerrier were workingon the same prediction, and that they in factcame to the same conclusion. Airy told neitherof them about the other’s work. On June 29 Airyreceived LeVerrier’s reply. With this information,he met with Challis and another astronomer, SIR

JOHN FREDERICK WILLIAM HERSCHEL (son of SirWilliam Herschel, discoverer of Uranus) to dis-cuss the “extreme probability of now discover-ing a new planet in a very short time . . .”

“It was so novel a thing to undertake ob-servations in reliance upon merely theoreticaldeductions; and that while much labour was

certain, success appeared very doubtful,” wroteChallis, but on July 29, he started the search byrecording stars in the area, which he would haveto observe and reobserve over several differentevenings, to compare locations and see if onehad moved. Since Challis did not have a cur-rent star map at the observatory, he could notmake quick comparisons. He made his secondobservation on July 30, his third on August 4,and his final observation on August 12, thenstarted comparing his data. Unfortunately, heonly looked at the first 39 stars he recorded onAugust 12 when he made the comparisons to theJuly 29 data. It was the 49th “star” that laterproved to be the planet, but Challis stopped hiscomparisons before finding this result.

In late August 1846 Hershel, who believedin the existence of the planet, suggested to afriend with a telescope that they could probablysee the planet just by looking for it in the sug-gested location. His friend, William Dawes, de-cided that the telescope he owned was not ade-quate enough, and searching for it would be awaste of time.

As it turned out, LeVerrier had the sameidea. On August 31 he published a paper withthe planet’s orbit, mass, and angular diameter,and suggested that using the data, they couldlook at the stars in this location, find the onethat was a disc rather than a point of light (plan-ets are disc-shaped in a telescope), and quicklyfind the planet.

On September 2 Adams sent Airy new com-putations with a more precise location of theplanet. Meanwhile, Dawes wrote to a friend,William Lassell, asking if he would use his largertelescope to help look for it. But Lassell had abadly sprained ankle and could not get around,so he gave the letter to his maid for safekeepingwhile he recovered. She promptly lost the let-ter, so Lassell never looked.

On September 10 Herschel gave a speechat a British Association event, in which hediscussed his belief in the new planet, and at

4 Adams, John Couch

which Adams was scheduled to present a paperon his findings. As if things could not becomea more dreadful comedy of errors, it turns outthat there was some confusion as to the sched-uled date of the presentation, and Adams arrivedat the session the day after it closed.

LeVerrier’s experience in getting the Frenchgovernment to search for the planet soon be-gan to resemble Adams’s experience with theBritish government: Interest was lacking. So, onSeptember 18 he wrote to the astronomer JOHANN

GOTTFRIED GALLE at the Berlin Academy, givinghim the calculations and asking him to searchwith his telescope. Galle and his assistant,Heinrich d’Arrest, received LeVerrier’s letter onSeptember 23, and since they had a telescopeand new star maps success seemed likely.Within the hour, the planet was found. Galleimmediately wrote to LeVerrier, “Monsieur, theplanet of which you indicated the position reallyexists.”

Back in England, Challis finally received acopy of LeVerrier’s August 31 paper, and he didsome more observations. This time he actuallysaw that one of the stars was a disc, but he pre-ferred to confirm that it was really a planet byobserving and comparing movement, whichwould take time, so he did nothing.

To the surprise of everyone involved, onOctober 1 London’s prestigious newspaper TheTimes announced Galle’s sighting of “LeVerrier’splanet.” Challis immediately looked through histelescope again and confirmed that the disc hesaw on July 29 had moved. By October 3 thescandal had begun.

Herschel informed the public that Adamshad made the same prediction earlier thanLeVerrier. The humble Adams was called uponto confirm the time and nature of his computa-tions, and Airy and Challis had to explain them-selves to the press and the public in light ofAdams’s virtually ignored, yet significant, work.

Naturally, the British government wantedthe credit for the finding, and so it claimed that

since they were the first to know about theplanet, it was a British discovery. The Frenchgovernment, absent in helping LeVerrier lookfor the planet, suddenly decided it was time totake action, so it claimed ownership of the dis-covery. And the Germans, who were the firstto actually see the planet, received no credit atall.

Additional investigations revealed that“LeVerrier’s planet” had been observed and cat-alogued by other, earlier astronomers, includingGalileo Galilei on December 28, 1612, andJanuary 27 and 28, 1613, who observed that ithad traveled but did not pursue it as a planetarydiscovery. The French astronomer Joseph-Jérôme Le Français de Lalande recorded it as astar on May 8 and 10, 1795, as did Herschel onJuly 14, 1830, and the Scottish-German as-tronomer Johann von Lamont on October 25,1845, and September 7 and 11, 1846.

To add to the debate, American scientistsattacked both Adams and LeVerrier, sayingthat their calculations of the planet’s orbitwere so far off (which they were) that its dis-covery was purely a coincidence. None of thisseemed to really affect the mild-manneredAdams, who simply did not get embroiled inany of it.

In 1847 John Herschel invited both Adamsand LeVerrier to meet with him at his home inKent. Despite the insistence by the British gov-ernment that Adams had discovered the planet,Adams himself apparently never made thatclaim, and it is considered common knowledgethat he was never bitter about any of it. He was,instead, a great admirer of LeVerrier’s, and uponmeeting at Herschel’s, the two apparently be-came good friends.

Adams survived the great fiasco, and bothhe and LeVerrier became recognized as thecodiscoverers of the new planet, named Neptune.Adams went on to participate in other signifi-cant astronomical work, including computa-tions on the acceleration of the Moon, and the

Adams, Walter Sydney 5

relationship of the Leonids (meteors that origi-nate from a region in the “head” of the constel-lation Leo) with a comet.

In 1848 Adams received the coveted CopleyMedal from the Royal Society of London, andin 1859 he became the Lowndean Professor of Astronomy and Geometry at CambridgeUniversity. He stayed in this position for thenext 32 years. In 1861 he succeeded Challis asthe director of the Cambridge Observatory, andlater served two terms as president of the RoyalAstronomical Society. Adams passed up twovery deserved opportunities for fame. He de-clined Airy’s job as Astronomer Royal whenAiry retired, and he refused a knighthood offeredby Queen Victoria because he apparently couldnot afford to keep up the standard of living of aknight.

Adams married Eliza Bruce (descendant ofScottish king Robert Bruce) in 1863. He retiredfrom Cambridge in 1891 and died in 1892. In1895 a memorial was placed in WestminsterAbbey near the memorial to Newton, and manybelieve that Adams was the greatest English as-tronomer and mathematician since SIR ISAAC

NEWTON. Adam’s memoir, which included thestory of his predictions, was published at somepoint during his life, under the title An explana-tion of the observed irregularities in the motion ofUranus, on the hypothesis of disturbances caused bya more distant planet; with a determination of themass, orbit, and position of the disturbing body. Acrater is named in honor of Adams on the sur-face of the Moon.

5 Adams, Walter Sydney(1876–1956)AmericanAstronomer

Walter Sydney Adams specialized in stellarspectroscopic studies and codeveloped the im-portant technique called spectroscopic parallax

for determining stellar distances. In 1915 hisspectral studies of Sirius B led to the discoveryof the first white dwarf star. From 1923 to 1946he served as the director of the Mount WilsonObservatory in California.

Walter Adams was born on December 20,1876, in the village of Kessab, near Antioch innorthern Syria, to Lucien Harper Adams andDora Francis Adams, American missionariesfrom New Hampshire. This area of Syria, whereAdams spent the first nine years of his child-hood, was then under Turkish rule as part of theformer Ottoman Empire. By 1885 his parents

Astronomers Walter Sydney Adams (left), JamesHopwood Jeans (center), and Edwin Powell Hubble(right) relax for a moment outdoors in spring 1931 atthe Mount Wilson Observatory, in the San GabrielMountains about 30 kilometers northwest of LosAngeles, California. Adams specialized in stellarspectroscopy and served as the director of MountWilson from 1923 to 1946. (Courtesy AIP EmilioSegrè Visual Archives)

6 Adams, Walter Sydney

had completed their missionary work and re-turned home to the United States.

As a student at Dartmouth College, Adamsearned a reputation as a brilliant undergraduate.He selected a career in astronomy as a result of his courses with Professor Edwin B. Frost(1866–1935). Adams graduated from Dartmouthin 1898 and then followed Frost to the Universityof Chicago’s Yerkes Observatory. While learningspectroscopic methods at the observatory, Adamsalso continued his formal studies in astronomyat the University of Chicago, where, in 1900,he obtained a graduate degree. The famousAmerican astronomer GEORGE ELLERY HALE

founded this observatory in 1897, and its 40-inchrefractor telescope was the world’s largest. As ayoung graduate, Adams had the unique oppor-tunity to work with Hale as he established a newdepartment devoted to stellar spectroscopy. Thisexperience cultivated Adams’s lifelong interestin stellar spectroscopy.

From 1900 to 1901 Adams studied in Munich,Germany, under several eminent German as-tronomers, including KARL SCHWARZSCHILD. Hethen returned to the United States and workedat the Yerkes Observatory on a program thatmeasured the radial velocities of early-type stars.In 1904 he moved with Hale to the newly es-tablished Mount Wilson Observatory, in the SanGabriel Mountains about 19 miles (30 km)northwest of Los Angeles, California. Adams be-came assistant director of this observatory in1913, and served in that capacity until 1923,when he succeeded Hale as director.

Adams married his first wife, Lillian Wickham,in 1910. After her death 10 years later, he mar-ried Adeline L. Miller in 1922, and the couplehad two sons, Edmund M. and John F. Adams.From 1923 until his retirement in 1946, Adamsserved as the director of the Mount WilsonObservatory. Following his retirement on January1, 1946, he continued his astronomical activi-ties at the Hale Solar Laboratory in Pasadena,California.

At Mount Wilson, Adams was closely in-volved in the design, construction, and opera-tion of the observatory’s initial 60-inch (1.5-m)reflecting telescope, and then the newer 100-inch (2.5-m) reflector that came on line in1917. Starting in 1914 he collaborated withthe German astronomer Arnold Kohlschütter(1883–1969) in developing a method of estab-lishing the surface temperature, luminosity (theamount of radiation a star emits), and distanceof stars from their spectral data.

In particular, Adams showed how it waspossible for astronomers to distinguish betweena dwarf star and a giant star simply from theirspectral data. As defined by astronomers, adwarf star is any main sequence star, while agiant star is a highly luminous one that has de-parted the main sequence toward the end of itslife and swollen significantly in size. Giant starstypically have diameters from 5 to 25 times thediameter of the Sun and luminosities that rangefrom tens to hundreds of times the luminosityof the Sun. Adams showed that it was possibleto determine the luminosity of a star from itsspectrum. This allowed him to introduce theimportant method of “spectroscopic parallax”whereby the luminosity deduced from a star’sspectrum is then used to estimate its distance.Astronomers have estimated the distance ofmany thousands of stars with this importantmethod.

Adams is perhaps best known for his workinvolving Sirius B, the massive but small com-panion to Sirius, the Dog Star—the brighteststar in the sky after the Sun.

The German mathematician and astronomerFRIEDRICH WILHELM BESSEL first showed in 1844that Sirius must have a companion and he evenestimated its mass to be about the same as thatof the Sun. In 1862 the American opticianALVAN GRAHAM CLARK made the first telescopicobservation of Sirius B, sometimes called thePup. Their preliminary work set the stage forAdams to make his great discovery.

Alfonso X 7

In 1915 Adams obtained the spectrum ofSirius B—a very difficult task due to the bright-ness of its stellar companion, Sirius. The spec-tral data indicated that the small star wasconsiderably hotter than the Sun. A skilled as-tronomer, he immediately realized that such ahot celestial object, just eight light-years dis-tant, could remain invisible to the naked eyeonly if it was very much smaller than the Sun.Sirius B is actually slightly smaller than Earth.Assuming all of his observations and reasoningwere true, Adams reached this important con-clusion: Sirius B must have an extremely highdensity, possibly approaching 1 million timesthe density of water.

So in 1915 Adams made astronomical his-tory by identifying the first “white dwarf”—asmall, dense object that is the end product ofstellar evolution for all but the most massivestars. A golf ball–sized chunk taken from thecentral region of a white dwarf star would havea mass of about 35,000 kilograms—that is, 35metric tonnes, or some 15 fully-equipped sportutility vehicles.

Almost a decade later, Adams parlayed hisidentification of this very dense white dwarf star.He assumed a compact object like Sirius Bshould possess a very strong gravitational field.He further reasoned that according to ALBERT

EINSTEIN’S general relativity theory, Sirius B’sstrong gravitational field should redshift anylight it emitted. Between 1924 and 1925 he suc-cessfully performed difficult spectroscopic meas-urements that detected the anticipated slightredshift of the star’s light. This work providedother scientists with independent observationalevidence that Einstein’s general relativity theorywas valid.

Adams also conducted spectroscopic inves-tigations of the Venusian atmosphere in 1932,showing that it was rich in carbon dioxide (CO2).He retired as director of the Mount WilsonObservatory in 1946, but continued his researchat the Hale Laboratory. He died peacefully at

home in Pasadena, California, on May 11, 1956.His numerous honors and awards for his con-tributions to astronomy include the HenryDraper Medal of the National Academy ofSciences (1918), the Gold Medal of the RoyalAstronomical Society (1917), and the BruceGold Medal from the Astronomical Society ofthe Pacific (1928). He became an associate ofthe Royal Astronomical Society in 1914 and amember of the National Academy of Sciencesin 1917.

5 Alfonso X (Alfonso el Sabio, Alfonso the Learned, Alfonso the Wise)(1221–1284)SpanishAstronomer, Historian

Alfonso X, dedicated to creating a Spanish-language encyclopedia filled with the knowl-edge of all of mankind, and particularly com-mitted to the study of astronomy, became animportant figure in this scientific field duringhis reign (1252–84) as king of León and Castile.Armed with the power and money to attractthe most brilliant minds in the known world,Alfonso ordered and oversaw the creation ofastronomy-based texts and tables that becamethe definitive work on the subject for threecenturies.

Astronomy and astrology were disciplinesthat were so closely intertwined during this erathat they were not considered two separatefields of study. The Moon and stars were con-sulted for a variety of practical purposes, in-cluding religion, timekeeping, medicine, andnavigation. Accurate and complete texts,charts, and tables were essential to govern theseimportant matters, and the key to creating thedefinitive source was to amass the largest quan-tity of information and then turn it into themost accurate translations.

8 Alfvén, Hannes Olof Gösta

These translations required experts in boththe languages and the subject matter. Whetherthe document was in Arabic, Greek, or Latin,each was to be translated into Spanish. Asidefrom simply transferring the information fromone language to another, translators were re-quired to correct and update the mathematicalcomputations. Experts in astronomy and geom-etry were essential to this process. It is saidAlfonso X brought together more than 50 of thegreatest minds from around the world to workon just one of these translations.

The most significant work to come out ofthis regime was the Alfonsine Tables. These ta-bles were calculations that, using Alfonso’s yearof coronation as the base year, gave exact rulesto compute the position of any of the planetsat any time. Derived from the Arabian ToledoTables, created in the middle of the 11th cen-tury by Abu Ishaq Ibrahim Ibm Yahya al-Zarqali (better known by his European name ofArzachel), the Alfonsine Tables resolved somediscrepancies of the earlier tables and were the“holy grail” of astronomical tables for the next300 years.

It is estimated that the Alfonsine Tableswere completed sometime between 1252 and1280, and it is known for certain that theyreached Paris in 1292, staying in use well intothe mid-1500s. NICOLAS COPERNICUS learnedabout the Alfonsine Tables while studying atthe university in Krakow, and he used them inhis computations as he developed his theoriesof a heliocentric universe. With Copernicus’scalculations, a new set of tables, the PrutenicTables, were developed in 1551 by ErasmusReinhold, and these became the new standardin astronomy.

In 1280 another huge undertaking wascompleted, the publishing of Libros del Saber deAstronomia, in which all of the known stars wereidentified and listed with their coordinates.Astronomical instruments were described, a va-riety of clocks were identified and detailed, and

PTOLEMY’S celestial spheres were explained ingreat detail in this text. Due to the complexityof the Ptolemaic system, in which the planets,Sun, and Moon each existed in their own cir-cle, each circled the Earth, and most requiredadditional circles to explain their motion,Alfonso X was so perplexed by Ptolemy’s ex-planation that he is quoted as saying, “Had Ibeen present at the creation, I would have givensome useful hints for the better ordering of theUniverse.”

Because of his dedication to astronomy andthe decree to amass the definitive collection oftexts, Alfonso X is responsible for the survivalof information from the ancient texts, which al-lowed their introduction to European societyand helped fuel the scientific advancements thatbegan during the Renaissance and continue tothis day.

5 Alfvén, Hannes Olof Gösta(1908–1995)SwedishPhysicist, Space Scientist, Cosmologist

Hannes Alfvén developed the theory of magne-tohydrodynamics (MHD), the branch of physicsthat helps astrophysicists understand sunspotformation and the magnetic field-plasma inter-actions (now called Alfvén waves in his honor)taking place in the outer regions of the Sun andother stars. For this pioneering work and its ap-plications to many areas of plasma physics, heshared the 1970 Nobel Prize in physics.

Hannes Olof Gösta Alfvén was born inNorrköping, Sweden, on May 30, 1908, toJohannes Alfvén and Anna-Clara Romanus,both practicing physicians. He began his highereducation at the University of Uppsala in 1926,and obtained his Ph.D. in philosophy in 1934.That same year, he received an appointment tolecture in physics at the University of Uppsala.

Alfvén, Hannes Olof Gösta 9

and joined the University of California at SanDiego as a visiting professor of physics, a posi-tion he held until 1991, when he retired. In1970 he shared the Nobel Prize in physics withthe French physicist Louis Néel (1904–2000).Alfvén received his half of the prize for his fun-damental work and discoveries in MHD and itsnumerous applications in various areas ofplasma physics.

Alfvén is best known for his pioneeringplasma physics research that led to the creationof the field of magnetohydrodynamics—thebranch of physics concerned with the interac-tions between plasma and a magnetic field.Plasma is an electrically neutral gaseous mixtureof positive and negative ions. Physicists often re-fer to plasma as the fourth state of matter, be-cause the plasma behaves quite differently fromsolids, liquids, or gases.

In the 1930s Alfvén went against conven-tional beliefs in classical electromagnetic theory.He boldly proposed a theory of sunspot forma-tion centered on his hypothesis that under cer-tain physical conditions a magnetic field can belocked or “frozen” in a plasma. He built uponthis hypothesis and further suggested in 1942that under certain conditions—as found, for ex-ample, in the Sun’s atmosphere—waves canpropagate through plasma influenced by mag-netic fields. Today solar physicists believe thatat least a portion of the energy heating the so-lar corona is due to action of these waves, Alfvénwaves, propagating from the outer layers of theSun.

Much of Alfvén’s early work on MHD and plasma physics is collected in the booksCosmical Electrodynamics (1948) and CosmicalElectrodynamics: Fundamental Principles, coau-thored in 1963 with the Swedish physicist Carl-Gunne Fälthammar (born 1931).

In the 1950s Alfvén again proved to be ascientific rebel when he disagreed with bothSteady State cosmology and Big Bang cosmology.Instead, Alfvén suggested an alternate cosmology

The Swedish physicist and Nobel laureate HannesAlfvén developed the theory of magnetohydrodynamics(MHD). This important branch of physics allowsastrophysicists to study sunspot formation and themagnetic field–plasma interactions that take place inthe outer regions of the Sun and other stars. Heappears here at a press conference after beingannounced as a co-winner of the 1970 Nobel Prize inphysics. (AIP Emilio Segrè Visual Archives)

He married Kerstin Maria Erikson in 1935, andthe couple had five children: one son and fourdaughters.

In 1937 Alfvén joined the Nobel Institutefor Physics in Stockholm as a research physicist.Starting in 1940, he held a number of positionsat the Royal Institute of Technology inStockholm. He served as an appointed profes-sor in the theory of electricity from 1940 to1945, professor of electronics from 1945 to1963, and professor of plasma physics from 1963to 1967. In 1967 he came to the United States

10 Alpher, Ralph Asher

based on the principles of plasma physics. Heused his 1956 book, On the Origin of the SolarSystem, to introduce his hypothesis that thelarger bodies in the solar system were formed bythe condensation of small particles from pri-mordial magnetic plasma. He further pursuedsuch electrodynamic cosmology concepts in his1975 book, On the Evolution of the Solar System,which he coauthored with Gustaf Arrhenius.

Alfvén also developed an interesting modelof the early universe in which he assumed thepresence of a huge spherical cloud containingequal amounts of matter and antimatter. Thistheoretical model, sometimes referred to asAlfvén’s antimatter cosmology model, is not cur-rently supported by observational evidence oflarge quantities of annihilation radiation—theanticipated by-product when galaxies and anti-galaxies collide. So while contemporary astro-physicists and astronomers generally disagreewith his theories in cosmology, Alfvén’s work inmagnetohydrodynamics and plasma physics re-mains of prime importance to scientists engagedin controlled thermonuclear fusion research.

After retiring in 1991 from his academic po-sitions at the University of California at SanDiego and the Royal Institute of Technology inStockholm, Alfvén enjoyed his remaining yearsby commuting semiannually between homes inthe San Diego area and Stockholm. He died inStockholm on April 2, 1995, and is best re-membered as the Nobel laureate theoreticalphysicist who founded the important field ofmagnetohydrodynamics.

5 Alpher, Ralph Asher(1921– )AmericanPhysicist, Cosmologist

In 1989 the National Aeronautics and SpaceAdministration (NASA) launched a $150 mil-lion satellite to investigate cosmic background

radiation in space, the existence of which wassuggested some 41 years earlier by the youngPh.D. student Ralph Alpher. Known for the con-cept that would eventually be dubbed the bigbang theory, Alpher was the first person to de-vise the equations that explained the origin ofthe universe.

Ralph Alpher was born in 1921 to Samueland Rose Alpher, and by the time he was 16, in1937, the inquisitive young man was ready toleave his family’s home in Washington, D.C., tostudy science at college. But it was the GreatDepression, and Alpher’s dream to study at theMassachusetts Institute of Technology (MIT) ona full scholarship was vanquished when thescholarship was inexplicably rescinded. So, theperseverant Alpher did what he thought wouldbest accomplish his goals. He enrolled in nightschool at George Washington University.

Working during the day as a secretary toearn enough money for school, books, and food,Alpher spent the next six years as an under-graduate, first studying chemistry, then switch-ing to physics. Science had taken hold of Alpherand would not let go. Acknowledging that therewas much more he wanted to learn and accom-plish, Alpher spent the next two years workingtoward his master’s degree, and then, in 1945,he jumped into the doctorate program.

Alpher’s thesis adviser was the renowned ex-Soviet scientist GEORGE GAMOW, who had theperfect project for Alpher. Gamow had given alot of thought to what might have happened atthe beginning of time to create the elements, buthe had dedicated little time to work on the prob-lem. Under Gamow’s supervision, Alpher was tofigure out the origin of the elements for his the-sis. To narrow it down, Gamow suggested thatAlpher not worry about the exact instant theuniverse was created, but rather look at what washappening when things started to stabilize andcool down to the point of containing radiationand ylem, the Greek term Gamow assigned tothe concept of the primordial soup of life.

Alpher, Ralph Asher 11

Alpher worked on the timing and themechanics, considering first how neutrons hadexisted and then radioactively decayed into pro-tons, electrons, and neutrinos; expanding, cool-ing, combining, creating the universe and all ofthe elements in it, all of which happened withinthe first five minutes of creation. These wereconcepts that no previous scientist had evenconsidered explaining.

Gamow was interested in making certainthat Alpher’s work would get as much attentionas possible. Since alpha, beta, and gamma are thefirst three letters of the Greek alphabet, Gamowmade a play on words to give Alpher’s work amemorable title. By adding another scientist’sname to the paper, HANS ALBRECHT BETHE, hecould call it the Alpher, Bethe, Gamow theory.Bethe refused to take credit for work he had notdone, but Gamow included his name on the pa-per anyway, and the publicity idea worked.Gamow sent the paper to The Physical Review forpublication, and the article was printed on April1, 1948. This became the hottest topic in thehistory of astronomy.

With Alpher’s thesis public, the idea thatthe universe was created by a superhot explosioncaused a scientific stir of great proportions.Alpher’s next task was to defend the work in hisoral exam, which under normal circumstanceswould take place in front of a handful of facultymembers. In this case, however, Alpher showedup to an audience of about 300 people, includ-ing the press and some of the most importantphysicists of the time. When Alpher was askedhow long the big bang took, and he respondedabout 300 seconds, he became instant fodder forheadlines and cartoons, and the recipient of allkinds of mail offering help for his soul because,as he said, “I had dared to trample on their con-cept of Genesis.”

This kind of notoriety required more workimmediately. Alpher teamed up with a col-league, Robert Herman, and the two wrote andpublished 18 more papers, the first of which was

published in Nature, a British scientific journal.This paper suggested that the best way to provethe theory was to look into space for the radia-tion that still existed from the event that oc-curred 15 billion years ago. The radiation, theyinsisted, would be within a blackbody spectrumthat would show up at about 5 kelvins (K), ap-proximately 450 degrees below zero Fahrenheit.The simple math for the proof boiled down tothis: The amount of radiation divided by theamount of matter that existed immediately af-ter the big bang is equal to the amount of radi-ation divided by the amount of matter that ex-ists now. This equation took Herman andAlpher an entire summer to devise, calculate,and substantiate.

Alpher’s biggest problems were twofold.First, a highly respected group of notable scien-tists had an entirely different view on how theuniverse worked. These “steady-state” physicistsincluded Fred Hoyle, who, ridiculing Alpher,came up with the term “big bang.” The secondproblem involved the technology, or lack of it,available at the time. Alpher and Herman sim-ply could not get their results verified becausebackground radiation in space, they were told,could not be measured. Despite their exhaustiveefforts to find a way, they came up with no help.

In 1955 Alpher and Herman left academiato earn a living in the corporate sector. Hermanworked for General Motors, and Alpher went toGeneral Electric (GE). Alpher wrote hundredsof papers for GE, but he and Herman wroteonly four more research papers together ontheir theory. In time, their revolutionary ideaswere forgotten.

Technology changed dramatically over thenext nine years. By 1964, two scientists, A. G.Doroschkevich and Igor Novikov, took upAlpher and Herman’s cause in a paper they pub-lished, suggesting a search for blackbody radia-tion. But no one seemed interested in the topic.

At the same time, two other scientists, bothradio astronomers working for Bell Laboratories,

12 Alvarez, Luis Walter

were testing a horn-shaped antenna hoping tomeasure radio waves and echoes from satellites,when they were plagued with a background mi-crowave noise that they could not get rid of nomatter what adjustments they tried. What actu-ally happened was that they had stumbled uponthe blackbody radiation Alpher and Hermanpredicted in their early work. Instead of gettingrid of the noise, ARNO ALLEN PENZIAS andROBERT WOODROW WILSON ended up discover-ing cosmic microwave background radiation—at 3.5 K, instead of the 5 K that Alpher andHerman had suggested.

Penzias and Wilson’s discovery was publishedin 1965, and almost immediately ended the de-bate between the steady-state and the Big Bangtheorists. This proved that the Big Bang theorywas correct and sparked the birth of cosmology asa dedicated science. But everyone seemed to haveforgotten the fact that Alpher, Herman, andGamow had predicted and calculated this radia-tion 17 years earlier, when radio astronomy was inits infancy and this kind of proof was impossible.

The three original scientists began a writingcampaign to reinform the scientific communityof the hot debate that evolved around the orig-inal predictions in 1948, but no one was inter-ested and they received little response. AlthoughAlpher and Herman did eventually receive theMagellanic Premium Award from the AmericanPhilosophical Society in 1975 for their discov-eries, they were not included in the most im-portant recognition a scientist can achieve. In1978 Penzias and Wilson won the Nobel Prizein physics for their discovery of cosmic mi-crowave background radiation.

Alpher’s Big Bang theory is considered oneof the Top Ten Astronomical Triumphs of theMillennium, according to the American PhysicalSociety News. He has been called by his col-leagues “arguably one of the most important sci-entists of the century.”

In 1989 Alpher and Herman were honoredguests at the launching of COBE, NASA’s Cosmic

Background Explorer. The satellite found exactlywhat it was looking for—cosmic backgroundradiation—precisely at 2.7° K, radiation ema-nating from everywhere.

Today, Alpher is a distinguished researchprofessor at Union College in New York. He isthe administrator of the university’s DudleyObservatory, which has a mission to “support re-search in astronomy, astrophysics, and the his-tory of astronomy.” Ralph Alpher is part of itsliving history.

5 Alvarez, Luis Walter(1911–1988)AmericanPhysicist

Luis Walter Alvarez, a Nobel Prize–winningphysicist, collaborated with his son, Walter, ageologist, to rock the scientific community in1980 by proposing an extraterrestrial catastro-phe theory. Called the “Alvarez hypothesis,” thispopular theory suggests that a large asteroidstruck Earth some 65 million years ago, causinga mass extinction of life, including the dinosaurs.Alvarez supported the hypothesis by gatheringinteresting geologic evidence—namely, the dis-covery of a worldwide enrichment of iridium inthe thin sediment layer between the Cretaceousand Tertiary periods. The unusually high ele-mental abundance of iridium has been attributedto the impact of an extraterrestrial mineralsource. The Alvarez hypothesis has raised a greatdeal of scientific interest in cosmic impacts, bothas a way to possibly explain the disappearanceof the dinosaurs and as a future threat to planetEarth that might be avoidable through innova-tions in space technology.

Luis Alvarez was born in San Francisco,California, on June 13, 1911, to Walter C. Alvarez,a prominent physician, and Harriet SmythAlvarez. In 1925 the family moved from SanFrancisco to Rochester, Minnesota, so his father

Alvarez, Luis Walter 13

could join the staff at the Mayo Clinic. Duringhis high school years, Luis spent the summersdeveloping his experimental skills by working asan apprentice in the Mayo Clinic’s instrumentshop. He initially enrolled in chemistry at theUniversity of Chicago, but quickly embracedphysics, especially experimental physics, with an

enthusiasm and passion that remained for a life-time. In rapid succession, he earned his bache-lor’s degree (1932), master’s degree (1934), andPh.D. in physics (1936) at the University ofChicago. He married Geraldine Smithwick in1936, and they had two children: a son (Walter)and a daughter (Jean). Almost two decadeslater, in 1958, Luis Alvarez married his secondwife, Janet L. Landis, with whom he had twoother children: a son (Donald) and a daughter(Helen).

After obtaining his doctorate in physicsfrom the University of Chicago in 1936, Alvarezbegan his long professional association with theUniversity of California at Berkeley. Only WorldWar II disrupted this affiliation. Alvarez con-ducted special wartime radar research at theMassachusetts Institute of Technology in Bostonfrom 1940 to 1943. He then joined the atomicbomb team at Los Alamos National Laboratoryin New Mexico (1944–45). He played a key rolein the development of the first plutonium im-plosion weapon. During the Manhattan Project,Alvarez had the difficult task of developing areliable, high-speed way to multipoint-detonatethe chemical high explosive used to symmet-rically squeeze the bomb’s plutonium core intoa supercritical mass. During the world’s firstatomic bomb test, called Trinity, on July 16,1945, near Alamogordo, New Mexico, Alvarezflew overhead as a scientific observer. He wasthe only witness to precisely sketch the firstatomic debris cloud as part of his report. He alsoserved as a scientific observer onboard one ofthe escort aircraft that accompanied the EnolaGay—the B-29 bomber that dropped the firstatomic weapon on Hiroshima, Japan, on August 6,1945.

After World War II Alvarez returned to theUniversity of California at Berkeley and servedas a professor of physics from 1945 until his re-tirement in 1978. His fascinating career as an ex-perimental physicist involved many interestingdiscoveries that go well beyond the scope of this

The Nobel laureate physicist Luis Walter Alvarezcollaborated with his geologist son Walter to rock thescientific community in 1980 when they proposed anextraterrestrial catastrophe theory. Also called the“Alvarez hypothesis,” their popular version of anancient catastrophe suggests that a large asteroidstruck Earth some 65 million years ago, causing themass extinction of most living creatures, including thedinosaurs. Luis Walter Alvarez received the 1968Nobel Prize in physics for his outstanding experimentalwork in nuclear particle physics. (Ernest OrlandoLawrence Berkeley National Laboratory, courtesy AIPEmilio Segrè Visual Archives)

14 Alvarez, Luis Walter

book. Before discussing his major contributionto modern astronomy, however, it is appropri-ate to briefly describe the brilliant experimen-tal work that earned him the Nobel Prize inphysics in 1968. Simply stated, Alvarez helpedstart the great elementary particle stampedethat began in the early 1960s. He did this bydeveloping the liquid hydrogen bubble chamberinto a large, enormously powerful research in-strument of modern high-energy physics. His in-novative work allowed teams of researchers atBerkeley and elsewhere to detect and identifymany new species of very-short-lived subnuclearparticles—opening the way for the developmentof the quark model in modern nuclear physics.

When an elementary particle passes throughthe chamber’s liquid hydrogen (kept at a tem-perature of –250 degrees Celsius), the cryogenicfluid is warmed to the boiling point along thetrack that the particle leaves. The tiny telltaletrail of bubbles is photographed and carefullycomputer-analyzed by Alvarez’s device. Nuclearphysicists then examine these data to extractnew information about whichever member ofthe “nuclear particle zoo” they have just cap-tured. Alvarez’s large liquid-hydrogen bubblechamber came into operation in March 1959,and almost immediately led to the discovery ofmany interesting new elementary particles. In aquite appropriate analogy, Alvarez’s hydrogenbubble chamber did for elementary particlephysics what the telescope did for observationalastronomy.

Just before his retirement from the Universityof California, Luis Alvarez became intrigued bya very unusual geologic phenomenon. In 1977his son Walter (born 1940) showed him an in-teresting rock specimen that he had collectedfrom a site near Gubbio, a medieval Italian townin the Apennine Mountains. The rock samplewas about 65 million years old and consisted oftwo layers of limestone: one from the Cretaceousperiod (symbol K, after the German wordKreide for Cretaceous) and the other from the

Tertiary period (symbol T). A thin (approximately1 centimeter) clay strip separated the two lime-stone layers.

According to geologic history, as this lay-ered rock specimen formed eons ago, the di-nosaurs flourished and then mysteriously passedinto extinction. Perhaps the thin clay stripcontained information that might answer thequestion of why the great dinosaurs suddenlydisappeared. Alvarez and Walter carefully ex-amined the rock and were puzzled by the pres-ence of a very high concentration of iridiumin the peculiar sedimentary clay. Here onEarth, iridium is quite rare and typically nomore than about 0.03 parts per billion arenormally found in the planet’s crust. Soongeologists discovered this same iridium en-hancement (sometimes called the “iridiumanomaly”) in other places around the world inthe same thin sedimentary layer (called the KTboundary) that was laid down about 65 millionyears ago—the suspected time of a great massextinction.

Since iridium is so rare in Earth’s crust and ismore abundant in other solar system bodies, theAlvarez team postulated that a large asteroid—about 6 miles (10 km) or more in diameter—had struck prehistoric Earth. This cosmic col-lision would have caused an environmentalcatastrophe throughout the planet. Alvarez rea-soned that such a giant asteroid would largelyvaporize while passing through Earth’s atmos-phere, spreading a dense cloud of dust particlesincluding large quantities of extraterrestrial irid-ium atoms uniformly around the globe. TheAlvarez team further speculated that after theimpact of this killer asteroid, a dense cloud ofejected dirt, dust, and debris would encircle theglobe for many years, blocking photosynthesisand destroying the food chains upon whichmany ancient animals depended.

When Alvarez published this hypothesis in1980, it created quite a stir in the scientific com-munity. In fact, the Nobel laureate spent much

Ambartsumian, Viktor Amazaspovich 15

of the last decade of his life explaining and de-fending his extraterrestrial catastrophe theory.Despite the geophysical evidence of a global irid-ium anomaly in the thin sedimentary clay layerat the KT boundary, many geologists and pale-ontologists still preferred other explanationsconcerning the mass extinction. While still con-troversial, the Alvarez hypothesis emerged fromthe 1980s as the most popular explanation of thedinosaurs disappearance.

Shortly after Alvarez’s death, two very in-teresting scientific events took place that gaveadditional support to the extraterrestrial catas-trophe theory. First, in the early 1990s, a ringstructure 112 miles (180 km) in diameter, calledChicxulub, was identified from geophysical datacollected in the Yucatán region of Mexico. TheChicxulub crater has been age-dated at 65 mil-lion years. The impact of an asteroid 10 kilo-meters in diameter would have created thisvery large crater, as well as caused enormoustidal waves. Second, a wayward comet calledShoemaker-Levy 9 slammed into Jupiter in July1994. Scientists using a variety of space-basedand Earth-based observatories studied how thegiant planet’s atmosphere convulsed after get-ting hit by a cosmic “train” of chunks, about 20kilometers in diameter, of this fragmentedcomet that plowed into the southern hemi-sphere of Jupiter. The comet’s fragments de-posited the energy equivalent of about 40 mil-lion megatons of trinitrotoluene (TNT), andtheir staccato impact sent huge plumes of hotmaterial shooting 1,000 kilometers above thevisible Jovian cloud tops.

About a year before his death in Berkeley,California, on August 31, 1988, Alvarez pub-lished a colorful autobiography entitled Alvarez,Adventures of a Physicist. In additional to his1968 Nobel Prize in physics, he received nu-merous other awards, including the CollierTrophy in Aviation (1946) and the NationalMedal of Science, personally presented to himin 1964 by President Lyndon Johnson.

5 Ambartsumian, Viktor Amazaspovich(1908–1996)ArmenianAstrophysicist

Viktor Ambartsumian founded the ByurakanAstrophysical Observatory in 1946 on MountAragatz, near Yerevan, Armenia. This facilityserved as one of the major astronomical obser-vatories in the former Soviet Union.Considered the father of Russian theoretical as-trophysics, he introduced the idea of stellar as-sociation into astronomy in 1947. His majortheoretical contributions to astrophysics in-volved the origin and evolution of stars, the na-ture of interstellar matter, and phenomena as-sociated with active galactic nuclei.

Ambartsumian was born on September 18,1908, in Tbilisi, Georgia (then part of the czaristRussian Empire). His father was a distinguishedArmenian philologist—a teacher of classicalGreco-Roman literature—so young Viktor wasexposed early in life to the value of intense in-tellectual activity. When he was just 11 years old,he wrote the first two of his many astronomicalpapers: “The New Sixteen-Year Period forSunspots” and “Description of Nebulae inConnection with the Hypothesis on the Originof the Universe.” His father quickly recognizedhis son’s mathematical talents and aptitude forphysics and encouraged him to pursue higher ed-ucation in St. Petersburg (then calledLeningrad), Russia. In 1925 Ambartsumian en-rolled at the University of Leningrad. Before re-ceiving his degree in physics in 1928, he pub-lished 10 papers on astrophysics. From 1928 to1931, he did his graduate work in astrophysics atthe Pulkovo Astronomical Observatory. This his-toric observatory near St. Petersburg was foundedin the 1830s by the German astronomer FriedrichGeorg Wilhelm von Struve (1793–1864) andserved as a major observatory for the Russian(Soviet) Academy of Sciences until its destruc-tion during World War II.

16 Anderson, Carl David

During the short period from 1928 to 1930,Ambartsumian published 22 astrophysics papersin various journals, while still a graduate studentat Pulkovo Observatory. The papers signifiedthe emergence of his broad theoretical researchinterests, and his scientific activities began toattract official attention and recognition fromthe Soviet government. At age 26, ViktorAmbartsumian was made a professor at theUniversity of Leningrad, where he soon organ-ized and headed the first department of astro-physics in the Soviet Union. His pioneeringacademic activities and numerous scientific pub-lications in the field eventually earned him thetitle of “father of Russian (Soviet) theoreticalastrophysics.”

Ambartsumian served as a member of thefaculty at the University of Leningrad from 1931to 1943, and was elected to the Soviet Academyof Sciences in 1939. During World War II, drawnby his heritage he returned to Armenia (then arepublic within the Soviet Union). In 1943 heheld a teaching position at Yerevan StateUniversity, in the capital city of the Republic ofArmenia. That year he also became a memberof the Armenian Academy of Sciences. In 1946he organized the development and constructionof the Byurakan Astrophysical Observatory.Located on Mount Aragatz, this facility servedas one of the major astronomical observatoriesin the Soviet Union. Ambartsumian served asthe director of the Byurakan AstrophysicalObservatory and resumed his activities investi-gating the evolution and nature of star systems.

In 1947 he introduced the important newconcept of stellar association—the very loosegroupings of young stars of similar spectral typethat commonly occur in the gas- and dust-richregions of the Milky Way Galaxy’s spiral arms.He was the first to suggest the notion that in-terstellar matter occurs in the form of clouds.Some of his most important work took place in1955, when he proposed that certain galactic ra-dio sources indicated the occurrence of violent

explosions at the centers of these particulargalaxies. The English translation of his influen-tial textbook, Theoretical Astrophysics, appearedin 1958 and became standard reading for as-tronomers-in-training around the globe.

His fellow scientists publicly acknowledgedAmbartsumian’s technical contributions andleadership by electing him president of theInternational Astronomical Union (1961–64)and president of the International Council ofScientific Unions (1970–74). His awards in-cluded the Janssen Medal from the FrenchAcademy of Sciences (1956), the Gold Medalfrom the Royal Astronomical Society in London(1960), and the Bruce Gold Medal from theAstronomical Society of the Pacific (1960).

On August 12, 1996, this eminent Armenianastrophysicist died at the Byurakan Observatory.He is best remembered for his empirical ap-proach to complex astrophysical problems deal-ing with the origin and evolution of stars andgalaxies. He summarized his most importantwork in the paper “On Some Trends in theDevelopment of Astrophysics,” published in theAnnual Review of Astronomy and Astrophysics,volume 18, 1980.

5 Anderson, Carl David(1905–1991)AmericanPhysicist

Carl David Anderson began his studies in sci-ence in 1923 at the California Institute ofTechnology as an electrical engineering student.But he soon discovered physics and changed dis-ciplines, and eventually changed the world witha scientific discovery that has been called one ofthe most momentous of the century.

Born in New York City on September 3,1905, Anderson was the only child of CarlDavid Anderson and Emma Adolfinja Ajaxson,Swedish immigrants. The family moved to Los

Anderson, Carl David 17

Angeles, California, when Anderson was seven,and he lived with his mother following his par-ents divorce soon after the move. Following aneducation in public schools, Anderson enrolledat a new college in Pasadena, the CaliforniaInstitute of Technology (Caltech), in 1923, andsoon became a student of Robert Millikan, whoin December 1923 was honored for his work onthe elementary charge of electricity and on thephotoelectric effect, as a Nobel laureate inphysics.

It was Millikan who kept Anderson atCaltech after his graduation in 1927. Despite thefact that Anderson had applied and been ac-cepted for a fellowship in doctoral studies at theUniversity of Chicago under Millikan’s sugges-tion to get experience someplace other thanCaltech, Millikan decided that he wanted thebright student to stay and work with him on cos-mic rays. Since this subject was the one Andersonmost wanted to pursue, he obliged, and workedon research and experiments under Millikan’sdirection at Caltech.

From 1927 to 1930, Anderson was a teach-ing fellow at the university while working on hisdoctoral dissertation. In 1930 he received hisPh.D. magna cum laude, again in physics engi-neering, with a thesis on the space distribution ofphotoelectrons ejected from various gases by X-rays. For the next three years, he worked withMillikan as a research fellow, excited about thepossibility to delve into the world of gamma rays,of which little was known. It was during this time,in 1932, that Anderson made a discovery thatwould soon earn him the coveted Nobel Prize.

Cosmic radiation was relatively new groundfor Millikan and his researchers. A young as-tronomer named PAUL ADRIEN MAURICE DIRAC

had suggested that positive and negative statesshould exist for all matter, but not much was un-derstood about it, and Milliken was extremelycurious. He assembled a team of researchers, in-cluding William Pickering, Victor Neher, andAnderson, to oversee a group of experiments that

would lead to some insights and discoveries in thisnew frontier.

Anderson’s responsibility was to head up theresearch with the Wilson chamber, a cylindricalglass “cloud chamber” filled with water vapor-saturated gas. According to Pickering, “the pres-sure is dropped suddenly so that the gas expandsand cools to a supersaturated state.” When anionized particle passes through the cylinder, avisible path of water droplets appears along itspath, which is photographed and analyzed by thescientific team.

Anderson needed to improve the conditionsof the Wilson chamber, for which Wilson won aNobel Prize in 1927, and decided to build a newerversion that had the effect of dropping the pres-sure much faster with the help of a piston and avacuum, changing the vapor to include a mixtureof alcohol and water, and boosting the electro-magnetic power to bend the path of ionized par-ticles. This was a key both to getting better pho-tographs and to finding the polarity of theparticle’s charge. When the new experiments withthe modified chamber also included Pickering’sGeiger counter readings of when a particle waspresent, Anderson ended up with more data, butalso with new results that caused great concern.It appeared that the particles were negativelycharged and positively charged. Electrons, ofcourse, could only be negative.

Anderson added one more modification to hisWilson chamber, a lead plate that would slowdown the rate of speed as a particle passed throughit, and therefore determine the direction the par-ticle traveled. He then photographed a particlethat was absolutely a positively charged electrontraveling upward through the cylinder. This wasno longer cause for concern; it was instead the dis-covery of a lifetime. Reported in the Proceedingsof the Royal Society in 1932, the newly discoveredpositron became one of the first new fundamen-tal particles. Anderson had discovered antimatter.

Anderson still wanted more. Despite the factthat his research was taking place during the Great

18 Ångström, Anders Jonas

Depression, when funding was virtually nonexist-ent, he wanted to see what else he could find atdifferent altitudes and latitudes. Anderson enlistedthe help of graduate student Seth Neddermey toperform what became known as the Pike’s Peakexperiment, in which they, with great difficultyand many setbacks, took their Wilson chamber toan elevation of 14,000 feet and spent six weeksphotographing particles. Nearly 10,000 photo-graphs later, Anderson had made his next greatdiscovery, a new particle called the muon (origi-nally called the mesotron, then the mu meson,then shortened to simply muon). For his work dur-ing his early years in physics, Anderson receivedhis first award in 1935, the Gold Medal of theAmerican Institute of the City of New York.

In 1936, at the age of 31, this assistant pro-fessor from Caltech borrowed $500 from Millikanto go to Sweden to accept his next award, theNobel Prize in physics, following in the footstepsof his mentor. Anderson was corecipient of theaward that year with VICTOR FRANCIS HESS

(1883–1964) who discovered cosmic radiation. Inpresenting the award, the Nobel Committee forPhysics applauded Anderson for “finding one ofthe building stones of the universe, the positiveelectron.” Anderson used half of his nearly$20,000 prize money to pay for his ill mother’smedical bills, and invested the rest in real estate.

In 1937 Anderson became an associate pro-fessor at Caltech, and the same year received theElliott Cresson Medal of the Franklin Institute, aswell as an honorary degree from ColgateUniversity. The following year, he was elected tothe National Academy of Sciences. Anderson be-came a full professor of physics at Caltech in 1940,and in 1945 won the Presidential Certificate ofMerit.

During World War II Anderson was in-volved in several projects to benefit the U.S.government. He turned down the position ofdirector of the atomic bomb project, but laterhelped the U.S. Navy, through Caltech, to de-velop a stable and reliable solid rocket propel-

lant. From 1941 though 1945, he participated inresearch for the Office of Scientific Research andDevelopment, the National Defense ResearchCommittee, and even traveled to Normandy,France, to observe rockets in use.

Anderson added a family to his life in 1946when, at age 41, he married Lorraine Bergmanand adopted her three-year-old-son MarshallDavid. From 1947 to 1948 he was president ofthe American Academy of Arts and Sciences.In 1949 two more honors were bestowed uponhim: an honorary degree from Temple Universityand a new son, David Anderson.

In his remaining years at Caltech, Andersoncontinued teaching, conducting individual re-search, and receiving awards for the work that wasthe foundation of cosmic physics. He earned theJohn Ericsson Medal of the American Society ofSwedish Engineers in 1960, and joined PresidentKennedy at a special White House dinner heldin 1962 in honor of the Nobel laureates. Thefollowing year brought an honorary degree fromGustavus Adolphus College, and his member-ship in the National Academy of Sciences be-came a chairmanship of the Physics section in1963, a position he held for three years.

Anderson retired from Caltech in 1970,leaving behind his positions as chairman of thefreshman admissions committee and chairmanof the Physics, Mathematics, and Astronomy di-visions, which he had occupied for the prioreight years. In 1976 Anderson was named pro-fessor of physics emeritus of the Caltech Boardof Trustees. He died on January 11, 1991, at theage of 85 following a brief illness.

5 Ångström, Anders Jonas(1814–1874)SwedishPhysicist, Astronomer

This famous 19th-century Swedish physicistand solar astronomer performed pioneering

Ångström, Anders Jonas 19

spectral studies of the Sun. In 1862 Ångströmdiscovered that hydrogen was present in the so-lar atmosphere and went on to publish a de-tailed map of the Sun’s spectrum, coveringother elements present as well. A special unitof wavelength, the angstrom (symbol Å), nowhonors his accomplishments in spectroscopyand astronomy.

Anders Jonas Ångström was born in Lögdö,Sweden, on August 13, 1814. His father was a

chaplain for the timber industry. Anders studiedphysics and astronomy at the University ofUppsala—founded in 1477, the oldest of theScandinavian universities—and graduated in1839 with his doctorate. Upon graduation,Ångström joined the university faculty as a lec-turer in physics and astronomy. For more thanthree decades, he remained at this institution,serving it in a variety of academic and researchpositions. In 1843 he became an astronomicalobserver at the famous Uppsala Observatory—the observatory founded in 1741 by AndersCelsius (1701–44). In 1858 Ångström becamechairperson of the physics department and re-mained a professor in that department for theremainder of his life.

Ångström performed important research inheat transfer, spectroscopy, and solar astronomy.With respect to his contributions in heat trans-fer phenomena, he developed a method tomeasure thermal conductivity by showing thatit was proportional to electrical conductivity.He was also one of the 19th-century pioneers ofspectroscopy. Ångström observed that an elec-trical spark produces two superimposed spectra.One spectrum is associated with the metal ofthe electrode generating the spark, while thespectrum is from the gas through which thespark passes.

He applied LEONHARD EULER’s resonancetheorem to his experimentally derived atomicspectra data and discovered an important prin-ciple of spectral analysis. In his paper “OptiskaUndersökningar” (“Optical investigations”) pre-sented to the Swedish Academy in 1853,Ångström reported that an incandescent (hot)gas emits light at precisely the same wave-length as it absorbs light when it is cooled.This finding represents Ångström’s finest re-search work in spectroscopy, and his results an-ticipated the spectroscopic discoveries of GUSTAV

ROBERT KIRCHHOFF (1824–87) that led to thesubsequent formulation of Kirchhoff ’s laws ofradiation.

Portrait of Anders Ångström as a young scientist. Thisfamous 19th-century Swedish physicist and solarastronomer performed pioneering spectral studies ofthe Sun. In 1862 he discovered that hydrogen waspresent in the Sun’s atmosphere and published adetailed map of the solar spectrum, covering otherelements present as well. (AIP Emilio Segrè VisualArchives)

20 Arago, Dominique-François-Jean

Ångström was also able to demonstrate thecomposite nature of the visible spectra of variousmetal alloys. His laboratory activities at theUniversity of Uppsala gave Ångström the hands-on experience in the emerging field of spec-troscopy necessary to accomplish his pioneeringobservational work in solar astronomy.

By 1862 Ångström’s initial spectroscopic in-vestigations of the solar spectrum enabled himto announce his discovery that the Sun’s at-mosphere contained hydrogen. In 1868 he pub-lished Recherches sur le spectre solaire (Researcheson the solar spectrum), his famous atlas of thesolar spectrum, containing his careful measure-ments of approximately 1,000 Fraunhofer lines.Unlike other pioneering spectroscopists—forexample, ROBERT WILHELM BUNSEN (1811–99)and Gustav Kirchhoff—who used an arbitrarymeasure, Ångström precisely measured the cor-responding wavelengths in units equal to oneten-millionth of a meter. Ångström’s map of thesolar spectrum served as a standard of referencefor astronomers for nearly two decades. In 1905the international scientific community honoredhis contributions by naming the unit of wave-length he used the “angstrom”—where oneangstrom (symbol Å) corresponds to a length of10–10 meter (one ten-millionth of a millimeter).

Physicists, spectroscopists, and microscopistsuse the angstrom when they discuss the visiblelight portion of the electromagnetic spectrum.The human eye is sensitive to electromagneticradiation with wavelengths between 4 and 7 31027 meter. Since these numbers are very small,scientists often find it convenient to use theangstrom in their communications. For exam-ple, the range of human vision can now be ex-pressed as ranging between 4,000 and 7,000angstroms (Å).

In 1867 Ångström became the first scientistto examine the spectrum of the aurora borealis,commonly known as the Northern Lights. Becauseof this pioneering work, his name is sometimesassociated with the aurora’s characteristic bright

yellow-green light. He was a member of theRoyal Swedish Academy (Stockholm) and theRoyal Academy of Sciences of Uppsala. In 1870Ångström was elected a fellow of the RoyalSociety in London, and in 1872 received itsprestigious Rumford Medal. Ångström died onJune 21, 1874, in Uppsala.

5 Arago, Dominique-François-Jean(1786–1853)FrenchMathematician, Astronomer, Physicist,Politician

Dominique-François-Jean Arago, born in 1786just before the French Revolution, became oneof the most renowned scientists ever to come outof Napoleon’s famous Parisian school, ÉcolePolytechnique.

Arago was a mathematician first in his ca-reer, but a lover of science foremost. In 1809, atthe age of 23, he became a full mathematics pro-fessor at the École Polytechnique with an ap-pointment as chair of analytical geometry. Thissame year, he was also elected into the Académiedes Sciences. His career was firmly set in placeat this early age, and within two years, he wasentrenched in scientific discovery.

Light and optics theories were fascinating toArago’s brilliant mind, and in 1811 he began tocontemplate the theories of polarization, howlight rays have different characteristics whenthey travel in different directions when re-flected. Using quartz crystals, he conductedexperiments on light that resulted in the dis-covery of chromatic polarization. Arago wascontacted by another scientist, Thomas Young,who, using Arago’s work, proposed the firsttransverse wave light theory. Another contem-porary, Augustine Fresnel, also wrote Aragoabout wave optics, and by 1815 Fresnel presentedhis theory, La diffraction de la lumière, to theAcadémie. Despite opposition, Arago completely

Arago, Dominique-François-Jean 21

backed Fresnel’s theory, which was in directconflict with the better-known corpuscular the-ory of light, in which light is made up of parti-cles, as explained by SIR ISAAC NEWTON. Thanksin part to Arago’s belief in Fresnel’s theories,they were finally proven to be correct.

In 1820 Arago became one of many scien-tists who became enthralled with the newlypublished theory of electromagnetism. Aragotook simple steps to create an experiment inwhich he ran a current through a wire and at-tracted iron filings to the current, creating thefirst electromagnet. His next major interest wasin sound waves. In 1822 Arago worked withGaspard de Prony in a cannon-firing experi-ment to attempt to determine how fast soundtraveled through air.

In 1824 Arago experimented with suspend-ing a magnetized needle above a copper disk, andnoticed that when the copper moved, the nee-dle moved. This was the basis for Faraday’s 1831discovery of electromagnetic induction. The fol-lowing year, in 1825, Arago was awarded theRoyal Society Copley Medal, and his experi-mentation continued, this time taking him intothe realm of compressing gases. His early work,along with that of Faraday and others, con-tributed to the foundation of work that contin-ued until 1906, which identified the criticaltemperature that would liquefy each of thepermanent gases.

Arago’s active interest in scientific discoveryhad far-reaching consequences. In 1816 NicéphorNiepce started work on a solution to making light-sensitive chemicals that would create a permanentphotograph, which he originally wanted to use forlithography. Ten years later, Niepce created a so-lution that worked on an eight-hour exposure. Heinvited the French painter Louis Daguerre to joinhim, and when Niepce died in 1833, Daguerrecontinued the work. Eventually he began to usesilver iodide and mercury vapor on the plate, witha hyposulphite of soda solution. Arago stepped inand insisted, in 1839, that the French government

pay Daguerre and Niepce’s son for the rest of theirlives to continue their work on the process. By1874 the highly developed plates and solutionswere capable of taking pictures at the very fast rateof 1/25 of a second, and astronomer Pierre-Jules-César Jannsen (1824–1907), codiscoverer of he-lium in 1868, took the first series of continuousphotographs of the transit of Venus. Before theend of the century, cinematography was createdfrom this same technology.

The discovery of Neptune, in 1846, is astied to Arago as it is to JOHN COUCH ADAMS,Sir George Airy, and URBAIN-JEAN-JOSEPH LE

VERRIER. Arago suspected in 1845 that theanomalies in Uranus’s orbit were cause by an as-yet-undiscovered planet. Arago assigned the taskof finding the planet to LeVerrier, who publishedhis papers before Adams and won credit for thenew planet, which Arago participated in nam-ing. When the great scandal took place over theownership of discovery, all of France, especiallyArago, staunchly defended LeVerrier’s claim.

Arago’s work with light and optics con-tributed to the creation of instruments that en-abled photographic study of planets and stars,and the ability to begin to measure their colorand radiation. Measuring and comparing thebrightness of stars through photometry was atheory first introduced in 1729 by Pierre Bouguerin his paper Essai d’optique sur la gradation de lalumière. SIR JOHN FREDERICK WILLIAM HERSCHEL

was the first astronomer to create a photometer,in 1836, and although improvements were madeduring the next decade, many problems re-mained with the glass, or the prisms, and themethods used to work the photometer. In 1850Arago’s knowledge of polarization led to thesolution when he suggested using a single objectglass and two Nicol prisms as a basis forcomparing brightness. Astronomers EDWARD

CHARLES PICKERING (1846–1919) and KarlFriedrich Zöllner (1800–60) made a slight ad-justment of the prisms and glass, and by 1860the photometer was perfected. Zöllner then

22 Aratus of Soli

began using the instrument for a new purpose,to measure the light reflected by planets.

The matter of light waves was one thatstayed with Arago throughout his lifetime. In1838 he worked on the theory of an experimentinvolving the comparison of the speed of lightthrough air versus water versus glass, but therewere problems actually conducting the experi-ment. In 1850 experimentation could finally be-gin, but Arago’s age and failing eyesight meantthat his colleagues Léon Foucault and HippolyteFizeau would have to carry out the work. Basedon his specifications, the two proved his theoryof light, in which the velocity of light decreasesas it passes through a denser medium. Arago diedshortly thereafter.

During his lifetime, Arago became a politi-cal figure campaigning for liberal reform in theFrench government. He was appointed as minis-ter of war and marine, and is credited for elimi-nating slavery throughout the colonies. He hasbeen honored for his lifetime contribution to sci-ence in many ways. Several Parisian streets barehis name, and he is one of 72 scientists com-memorated with a plaque in the Eiffel Tower.The Moon and Mars each have a crater namedArago.

5 Aratus of Soli(ca. 315–ca. 245 B.C.E.)GreekWriter

Prior to the famous publication of Phaenomena,by Aratus of Soli, the texts of astronomy in an-cient Greece were mostly concerned with ex-planations of the spherical nature of the homo-centric system, as detailed by Eudoxus of Cnidos,who died approximately 35 years before Aratuswas born. The ordering of the heavens and thenature of their movement in relationship to theEarth and Sun, the reasoning behind why thestars moved from east to west, month to month,

and year to year, plus the description of the pathsthat were traveled in orbit, were all explainedmathematically in an elaborate scheme of sphereswithin spheres, each system of spheres inde-pendent of the others.

Aratus of Soli was not an astronomer or ascientist as we would classify these roles today,but his contribution to astronomy was one of thegreatest from ancient times, and had an impacton the works of Hipparchus and, eventually,PTOLEMY, centuries later.

Aratus was a Stoic who lived at the court ofthe Stoic king, Antigonus Gonatus of Macedonia.It is estimated that sometime around 270 B.C.E.,Aratus wrote the poem Phaenomena, which ex-plained the work of Eudoxus, not in detailedmathematical terms, but rather in simple verse,making the information more accessible toeveryone. This document gave the positions ofthe stars, their risings and settings, and descrip-tions of 44 constellations, all under the pretenseof a poem.

Hipparchos was the next astronomer towork with Aratus’s poem, in the first centuryB.C.E. The next great astronomer to come along,Ptolemy, also used the text as a basis for hiswork, and expanded the number of constella-tions to 48.

Phaenomena was considered such an impor-tant work that it transcended time. It was trans-lated from Greek into Latin and remained oneof the predominate textbooks on astronomy wellinto the 16th century.

5 Argelander, Friedrich Wilhelm August(1799–1875)GermanAstronomer

This 19th-century German astronomer investi-gated variable stars and compiled a major tele-scopic (but prephotography) survey of all the starsin the Northern Hemisphere brighter than the

Argelander, Friedrich Wilhelm August 23

ninth magnitude. From 1859 to 1862 Argelanderpublished the four-volume star catalog entitledBonner Durchmusterung (Bonn survey), an amaz-ing compendium containing more than 324,000stars.

Friedrich Argelander was born on March 22,1799, in the Baltic port of Memel, East Prussia(now Klaipeda, Lithuania). His father was awealthy Finnish merchant and his mother aGerman. He studied at the University ofKönigsberg in Prussia, where he was one ofFRIEDRICH WILHELM BESSEL’s most outstandingstudents. In 1820 Argelander decided to pursueastronomy as a career after becoming Bessel’s as-sistant at the Königsberg Observatory.

Argelander received his Ph.D. in astronomyin 1822 from the University of Königsberg. Hisdoctoral dissertation involved a critical reviewof the celestial observations made by JohnFlamsteed. Argelander’s academic research in-terest in assessing the observational quality ofearlier star catalogs so influenced his laterprofessional activities that the hardworking as-tronomer would eventually develop BonnerDurchmusterung, his own great catalog of NorthernHemisphere stars.

In 1823 Bessel’s letter of recommendationhelped Argelander secure a position as an ob-server at the newly established Turku (Åbo)Observatory in southwestern Finland (then anautonomous grand duchy within the ImperialRussian Empire). Here, the young astronomerpoured his energies into the study of stellar mo-tions. Unfortunately, a great fire in September1827 totally destroyed Turku, the former capitalof Finland, halting Argelander’s work at the ob-servatory. Following this catastrophe, the entireuniversity community moved from Turku to thenew Finnish capital at Helsinki.

In 1828 the university promoted Argelanderto the rank of professor of astronomy and alsogave him the task of designing and constructinga new observatory. Argelander found a suitablesite on a hill south of Helsinki and construction

was completed in 1832. This beautiful and ver-satile observatory served as the model for thePulkovo Observatory constructed by FriedrichGeorg Wilhelm von Struve (1793–1864) nearSt. Petersburg (Leningrad) for use as the majorobservatory of the Imperial Russian Empire.

Argelander summarized his work on stellarmotions in the 1837 book About the ProperMotion of the Solar System. His work in Helsinkiended in 1837 when Bonn University in his na-tive Prussia offered him a professorship in as-tronomy that he could not refuse. The offer in-cluded construction of a new observatory atBonn, financed by the German crown princeFriedrich Wilhelm IV (1795–1861), who be-came king in 1840. Argelander was a personalfriend of Friedrich Wilhelm IV, having offeredthe crown prince refuge in his own home inMemel, following Napoleon’s defeat of thePrussian army in 1806.

The new observatory in Bonn was inau-gurated in 1845. From then on, Argelanderdevoted himself to the development and pub-lication of his famous star catalog, BonnerDurchmusterung, which was published between1859 and 1862. Argelander and his assistantsworked very hard measuring the position andbrightness of 324,198 stars in order to compilethe largest and most comprehensive star cata-log ever produced without the assistance ofphotography. Argelander’s enormous worklisted all the stars observable in the NorthernHemisphere down to the 9th magnitude. In1863 Argelander founded the AstronomischeGesellschaft (Astronomical Society), whose mis-sion was to continue his work by developing acomplete celestial survey using the cooperationof observers throughout Europe.

Friedrich Argelander died in Bonn onFebruary 17, 1875. His assistant and succes-sor, Eduard Schönfeld (1828–91), extendedArgelander’s astronomical legacy into the skiesof the Southern Hemisphere by adding an-other 133,659 stars. Schönfeld’s own efforts

24 Aristarchus of Samos

ended in 1886, but other astronomers continuedArgelander’s quest. In 1914 the CordobaDurchmusterung (Cordoba Survey) appeared,containing the position of 578,802 SouthernHemisphere stars measured down to the 10thmagnitude, as mapped from the Córdoba obser-vatory in Argentina. This effort completed thehuge systematic (pre-astrophotography) surveyof stars begun by Bessel and his hardworking as-sistant Argelander nearly a century before.

5 Aristarchus of Samos(ca. 320–ca. 250 B.C.E.)GreekMathematician, Astronomer

In the mid-1600s, NICOLAS COPERNICUS revealedhis revolutionary idea of a heliocentric universe.While Copernicus remains one of the mostrenowned astronomers of all time, it was theGreek astronomer and mathematician Aristarchus,born on the island of Samos, who first intro-duced the concept that the Earth revolvedaround the Sun, some 17 centuries beforeCopernicus was born.

Little has been found through the ages aboutAristarchus’s work. It is believed that he studiedunder Strato of Lampsacus at ARISTOTLE’s Lyceumin Alexandria, sometime after 287 B.C.E. Severalauthors of other treatises have referred to his work,giving some historical perspective on his contri-bution to both astronomy and mathematics, aswell as the opinions of his work during the time.

The only remaining text found to date writ-ten by Aristarchus is a document entitledTreatise on the Sizes and Distances of the Sun andMoon. The significance of this piece has noth-ing to do with whether the Sun or the Earth isthe center of the universe, but rather with thefact that he reasoned, through mathematics andobservation of reflected sunlight on the surfaceof the Moon, a method to determine the rela-tionships between the Moon, Earth, and Sun

without the benefit of instruments or trigonom-etry. He calculated that the Sun was 20 timesthe size of the Moon, and 20 times as far fromthe Earth as the Moon. Through modern as-tronomy we know that his calculations were offby an order of magnitude, but the fact that hewas even able to make this kind of measurementwas of great importance to science.

Through the writings of the Roman archi-tect Vitruvius (90–20 B.C.E.), we get some indi-cation of Aristarchus’s importance in this fieldof study. He mentions Aristarchus amongothers in acknowledging their contribution to mathematical principles and inventions(Aristarchus is also credited for inventing abowl-shaped sundial).

It is through the works of Archimedes(287–12 B.C.E.) and Plutarch (45–125) thatAristarchus’s theory of a heliocentric system canbe found. While a critic of Aristarchus’s notionthat the Sun, not the Earth, is the center of theuniverse, Archimedes makes it clear thatAristarchus gets the credit for being the first topropose such an idea, as well as the first to sug-gest that the universe is enormous, much largerthan ever believed. Plutarch’s writings show thatAristarchus also believed that, despite how itmight appear that the stars rotate around theEarth, the truth was actually that the Earthrotated on its axis.

Aristarchus’s work was key in introducingthe concept of mathematical astronomy. Likemany astronomers in the centuries to come, thisstudent of the cosmos suffered from criticismthat his outrageous theories denied both math-ematical and religious known “truths.”

5 Aristotle(384–322 B.C.E.)GreekPhilosopher

Aristotle’s approach to astronomy differed littlefrom his approach to all of the other fields of

Aristotle 25

knowledge he pursued. He looked at everything,including the universe, as an organism. His ideason the order of the heavens were just a smallpart of the volumes he amassed for the purposeof teaching, and like the rest of Aristotle’s phi-losophy, his views on astronomy went unchal-lenged for centuries.

The son of a medical doctor namedNicomachus and his wife Phaestis, Aristotle wasborn in 384 B.C.E. in the northern Greek city ofStagirus. As the son of a physician, Aristotle wasdestined to learn about organisms and how liv-ing beings worked, because the practice of med-icine at the time was handed down from fatherto son as sacred, secret knowledge. But his par-ents died when he was about 10 years old, andhis travels and instruction with his father, whowas the personal physician to Amyntas III, theking of Macedonia, came to an end. Aristotlewas thereafter raised and educated in rhetoric,poetry, writing, and Greek by Proxenus ofAtarneus.

By the time Aristotle was 17, he was readyfor higher education, and went to study at theinstitution that PLATO founded 20 years earlier,the Academy in Athens, named after the Greeklandowner Academus. Eudoxus (ca. 400–347B.C.E.) was acting head of the university whenPlato traveled for political purposes, givingAristotle direct exposure to Eudoxus’s work.Aristotle’s philosophy soon began to be no-ticed, and Plato consistently referred to his fa-mous student as “the intelligence of theschool.”

Aristotle’s primary philosophy was basedin nature, and he believed that everythingcould easily, and logically, be explained throughobservation. It was this application of logic tohis observations that made it possible forAristotle to devise such convincing explana-tions that his ideas became intellectually irre-proachable.

In 347 B.C.E., upon Plato’s death, Aristotlewas not named to succeed his teacher as the head

of the Academy. Dedicated to learning, he be-gan a personal journey of acquiring and collect-ing knowledge, writing down his observationsand thoughts on topics ranging from biology andzoology, to logic and politics. He left Athens andtraveled first to Assos, where he married Pythias,the niece and adopted daughter of the rulerHermias of Atarneus, and had a daughter alsonamed Pythias. He went on to Lesbos, then toMacedonia in 343, staying at the court of KingPhilip, son of Amyntas III. During his stay inMacedonia, Aristotle endured the death of hiswife, and eventually met Herpyllis, with whomhe had a son, Nicomachus. When internal po-litical problems arose, Aristotle supported theviews of Philip’s son, Alexander, who soon be-came King Alexander the Great. Alexandersupported the works of the university, and askedAristotle to start another university of his ownin Athens.

In 335 B.C.E. Aristotle founded the Lyceum,bringing with him all of the writing he had ac-cumulated over the years. The Lyceum becamefamous for its teachings and discussions, whichoften took place between students and instruc-tors as they walked around the school, causingit to be referred to as the Peripatetic school,meaning “walking about.”

Aristotle believed that “a man could notclaim to know a subject unless he was capableof transmitting his knowledge to others, and heregarded teaching as the proper manifestation ofknowledge.” Aristotle’s knowledge, in additionto politics, psychology, economics, logic, zoology,ethics, poetry, rhetoric, and theology, includedastronomy, meteorology, chemistry, geography,physics, and metaphysics, many of which did notexist as fields of study until he created them.

There were some underlying philosophicalconcepts that led to his overall view of how theuniverse worked; and the logic that he imple-mented and applied to all science had to follow.First, Aristotle was a theoretical scientist. Hisideas were based on philosophical speculation,

26 Aristotle

never on scientific measurement, and weresomewhat guided by the knowledge and cultureof the time. His place was to give these theoriesa sense of order. Additionally, Aristotle did notbelieve in the mathematical concept of “infi-nite.” Logic prevailed, and he ordered astronomyaround the fact that the universe was finite.

His works On the Heavens and On Physicswere two of the main texts concerning Aristotle’sorder of the universe. Having studied underEudoxus, Aristotle expounded on the work of histeacher regarding the spherical definition of theplanets, Earth, Moon, Sun, and stars. He be-lieved that all of these were shaped like spheres,and that all existed in spheres, because spheresare the perfect shape. It was in fact logical, andbecame common knowledge, that the Earth wasa sphere, based on the arch of the shadow of alunar eclipse, and the appearance of new stars inthe horizon as one walked north.

Unlike Eudoxus, however, Aristotle be-lieved that these spheres actually physically ex-isted. The heavens, he said, were divided intotwo distinct parts. Everything below the Moon,in the subluminary sphere, contained the fourelements of earth, air, fire, and water, and thiswas the part of the universe where all changeoccurred, accounting for the existence ofgrowth, maturity, corruption, death, and decay.

Everything above the Moon, however, ex-isted in a pure, unchanging, eternal quintes-sence, or fifth element, which he called aether.In these spheres, the heavens were in constantspherical movement, and they never stopped orchanged because change did not exist. Thiscaused two problems. First, additional sphereshad to be added to make the whole system work,and second, there was an issue with the logic ofmotion.

Aristotle changed the spherical layoutEudoxus had devised by adding 22 more spheresto explain how the motion of some of the spheresworked in a way that would not interfere withthe motion of others. With the Earth at the cen-

ter, there were now 55 concentric spheres, all at-tached, all rotating at different velocities, work-ing in the complex way that an organism works.Aristotle also used this system to explain whystars twinkled. It was the movement of thespheres, he concluded, that caused friction andheated the air around a star, “particularly in thepart where the sun is attached to it,” and thatfriction explained why a star shines.

To address the issue of motion, Aristotle cre-ated another explanation. Since everything thatis in motion has to be set in motion, Aristotlecreated the existence of a Prime Mover, respon-sible for the initial movement of all of nature.He argued that this Prime Mover exists in theoutermost sphere of the universe, that it causesthe circular motion, which is perfect because ithas no beginning and no end, and that this ac-tivity because of its perfection is the highest formof joy. Since the universe is finite, nothing ex-ists beyond the limits of the universe, and sinceeverything is an organism, this highest degree oflife in the cosmos must reside in the sphere ofthe aether.

In the 13th century, the medieval theologianThomas Aquinas (1225–74) found translationsof Aristotle’s teaching notes on astronomy, andconvinced the church to use this work as thebasis for explaining Christianity. When thechurch adopted these philosophies as the foun-dation for the structure of the universe to ex-plain heaven and God, it became the word ofGod, and questioning Aristotle was tanta-mount to questioning God. This is what gotGALILEO GALILEI in trouble, and is, in part,what kept Aristotle’s work unchallenged for2,000 years.

Most of Aristotle’s writings published dur-ing his lifetime are lost. Only quoted fragmentsremain in the work of others. The writings thatdo exist from Aristotle consist of his lecturenotes from courses at the Lyceum, more than2,000 pages, although it is generally believedthat at least some of this material has been added

Arrhenius, Svante August 27

to by other teachers, students, and translatorsover the centuries.

In 323 Alexander the Great died, and pol-itics again caused Aristotle to leave Athens. Hemoved to his mother’s family estate in Chalcis,and died the following year, 322, at the age of62. Aristotle is now a crater on the Moon.

5 Arrhenius, Svante August(1859–1927)SwedishChemist, Exobiologist

Years ahead of his time, Svante August Arrheniuswas the pioneering physical chemist who wonthe 1903 Nobel Prize in chemistry for a brilliantidea that his conservative doctoral dissertationcommittee barely approved in 1884. His wide-ranging talents anticipated such Space Agescientific disciplines as planetary science andexobiology. In 1895 Arrhenius became the firstscientist to formally associate the presence of“heat trapping” gases, such as carbon dioxide, ina planet’s atmosphere with the greenhouse ef-fect. Then, early in the 20th century, he causedanother scientific commotion when he boldlyspeculated about how life might spread fromplanet to planet and might even be abundantthroughout the universe.

Arrhenius was born on February 19, 1859,in the town of Vik, Sweden, on the Universityof Uppsala’s estates, to Carolina ChristinaThunberg and Svante Gustaf Arrhenius, a landsurveyor responsible for managing the estates.His uncle, Johan Arrhenius, was a well-respectedprofessor of botany and rector of the Agricul-tural High School near Uppsala who also servedas the secretary of the Swedish Academy ofAgriculture.

In 1860 Arrhenius’s family moved toUppsala. While a student at the CathedralSchool, he demonstrated his aptitude for arith-metical calculations and developed a great

interest in mathematics and physics. Upon grad-uation in 1876, he entered the University ofUppsala, where he studied mathematics, chem-istry, and physics. He earned his bachelor’sdegree from the university in 1878, and con-tinued his studies there for an additional threeyears as a graduate student. However, Arrheniusencountered professors at the University ofUppsala who dwelled in what he felt was too

In 1908 the Nobel laureate Svante August Arrheniusintroduced the panspermia hypothesis when hepublished his book Worlds in the Making. Hishypothesis was a bold speculation that life couldspread through outer space from planet to planet bythe diffusion of spores, bacteria, or othermicroorganisms. He was also one of the first scientiststo anticipate global warming issues, when hepresented a paper at the end of the 19th century thatdiscussed the role of carbon dioxide as a heat-trapping gas in Earth’s atmosphere. (Elliot V. Fry,courtesy AIP Emilio Segrè Visual Archives)

28 Arrhenius, Svante August

conservative a technical environment and whowould not support his innovative doctoral re-search topic involving the electrical conduc-tivity of solutions. So in 1881 he went toStockholm to perform his dissertation researchin absentia under Professor Eric Edlund at thePhysical Institute of the Swedish Academy ofSciences.

In this more favorable research environment,Arrhenius pursued his scientific quest to answerthe mystery in chemistry of why a solution of salt-water conducts electricity when neither salt norwater do by themselves. His brilliant hunch was“ions”—that is, electrolytes that when dissolvedin water split or dissociate into electrically oppo-site positive and negative ions. In 1884 he pre-sented this scientific breakthrough in his thesis,“Recherches sur la conductibilité galvanique des élec-trolytes” (“Investigations on the galvanic conduc-tivity of electrolytes”). But, the revolutionarynature of Arrhenius’s ionic theory simply over-whelmed the orthodox thinkers on the doctoralcommittee at the University of Uppsala. Theyjust barely passed him, giving his thesis theequivalent of a blackball fourth-class rank anddeclaring only that his work was “not withoutmerit.”

Undeterred, Arrhenius accepted his doc-toral degree, continued to promote his new ionictheory, visited other innovative minds through-out Europe, and explored new areas of sciencethat intrigued him. For example, in 1887 heworked with LUDWIG BOLTZMANN in Graz,Austria. In 1891 Arrhenius accepted a positionas a lecturer in physics at the StockholmsHögskola, Stockholm’s Technical University. InStockholm in 1894, he married his first wife,Sofia Rudeck, his student and assistant. The fol-lowing year, he received a promotion to profes-sor in physics and the newly married couple hada son, Olev Wilhelm. But his first marriage wasa brief one, ending in divorce in 1896.

The Nobel Prize committee viewed thequality of Arrhenius’s pioneering work in ionic

theory quite differently than did his doctoralcommittee. It awarded Arrhenius the 1903Nobel Prize in chemistry “in recognition of theextraordinary services he has rendered to the ad-vancement of chemistry by his electrolytic the-ory of dissociation.” At the awards ceremony inStockholm, he met another free-spirited genius,Marie Curie (1867–1934), who shared the 1903Nobel Prize in physics with her husband, PierreCurie (1859–1906), and A. Henri Becquerel(1852–1908) for the codiscovery of radioactiv-ity. Certainly, 1903 was an interesting and chal-lenging year for the members of the Nobel Prizeselection committee. Arrhenius’s great discoveryshattered conventional wisdom in both physicsand chemistry, while Marie Curie’s pioneeringradiochemistry discoveries forced the committeeto include her as a recipient, making her the firstwoman to receive the prestigious award.

In 1905 Arrhenius retired from his profes-sorship in physics and accepted a position as thedirector of the newly created Nobel Institute ofPhysical Chemistry in Stockholm—a positionexpressly tailored by the Swedish Academy ofSciences to accommodate his wide-rangingtechnical interests. That same year, he marriedhis second wife, Maria Johansson, who bore himtwo daughters and a son.

Soon a large number of collaborators cameto the Nobel Institute of Physical Chemistryfrom all over Sweden and numerous other coun-tries. The institute’s creative environment al-lowed Arrhenius to spread his many ideas far andwide. Throughout his life, he took a very livelyinterest in various branches of physics and chem-istry and published many influential books, in-cluding Textbook of Theoretical Electrochemistry(1900), Textbook of Cosmic Physics (1903),Theories of Chemistry (1906), and Theories ofSolutions (1912).

In 1895 Arrhenius boldly ventured into thefields of climatology, geophysics, and even plan-etary science, when he presented an interestingpaper to the Stockholm Physical Society. Titled

Aryabhata 29

“On the Influence of Carbonic Acid in the Airupon the Temperature of the Ground,” the pa-per anticipated by decades contemporary con-cerns about the greenhouse effect and the risingcarbon dioxide (carbonic acid) content in Earth’satmosphere. In the article, Arrhenius argued thatvariations in trace atmospheric constituents, es-pecially carbon dioxide, could greatly influenceEarth’s overall heat (energy) budget.

During the next 10 years, Arrhenius con-tinued his pioneering work on the effects of car-bon dioxide on climate, including his concernabout rising levels of anthropogenic (human-caused) carbon dioxide emissions. He summa-rized his major thoughts on the issue in his 1903book Lehrbuch der kosmichen Physik (Textbook ofcosmic physics)—an interesting work for plane-tary science and Earth system science, scientificdisciplines that did not yet exist.

A few years later, in 1908, Arrhenius pub-lished the first of several of his popular techni-cal books, Worlds in the Making. In this book, hedescribes the “hot-house theory” (now called thegreenhouse effect) of the atmosphere. He wasespecially interested in explaining how high-latitude temperature changes could promote theonset of the ice ages and interglacial periods.

In Worlds in the Making, he also introducedhis “panspermia” hypothesis—a bold speculationthat life could be spread through outer spacefrom planet to planet or even from star systemto star system, by the diffusion of spores, bacte-ria, or other microorganisms.

In 1901 he was elected to the SwedishAcademy of Sciences despite lingering academicopposition in Sweden to his internationally rec-ognized achievements in physical chemistry. TheRoyal Society of London awarded him the DavyMedal in 1902, and in 1911 elected him as a for-eign member. That same year, during a visit tothe United States, he received the first WillardGibbs Medal from the American ChemicalSociety. Finally, in 1914 the British ChemicalSociety presented him with its prestigious

Faraday Medal. He remained intellectually ac-tive as the director of the Nobel Institute ofPhysical Chemistry until his death in Stockholmon October 2, 1927.

5 Aryabhata (Aryabhata I, Aryabhata the Elder)(476–550)IndianMathematician, Astronomer

Born in India in 476, Aryabhata is consideredto be one of the most brilliant originalthinkers in mathematics and astronomy, mak-ing computations and explaining the nature ofour solar system some 1,000 years beforeNICOLAS COPERNICUS suggested the heliocen-tric system.

The exact years of Aryabhata’s birth anddeath are fixed from 476 to 550, but the loca-tion of his birthplace has never been determinedwith any consensus. Drawing conclusions fromtexts others have written about him, many ex-perts believe he was born in Kerala or one of anumber of other cities in southern India. Somebelieve he was born in Bengal in the northeast,while others suspect that it was Pataliputra inthe north, or the more common assumption ofKusumapura, which is thought to be current-dayPatna, but even the exact location of this an-cient city is unclear.

It is agreed, however, that Aryabhata didmost, if not all, of his work in Kusumapura, oneof the mathematical capitals of India, and thataround the year 499 he wrote the Aryabhatiya,the only surviving text of several he is believedto have written concerning astronomy. TheAryabhatiya is written in 121 verses, or couplets,on mathematics and astronomy. The first sec-tion is an introduction to some of the mathe-matics in the document. The next collection of33 verses covers algebra, trigonometry, frac-tions, and equations, and includes the accurate

30 Aryabhata

estimate of the value of pi, which he concludedwas 62732/20000, or 3.1416. The remainder ofthe text focuses on the heavens.

Aryabhata’s astronomy is one of many firsts.He is the first to describe the Earth as a sphere,and as a planet that rotates about its axis. It isthis rotation, he explains, that makes the nightsky appear to move above us.

His work also looks at the relationships be-tween the Sun, the Earth, and the Moon. He isthe first to compute the ratio between lunarorbits and rotations of the Earth, and also tocalculate the length of the solar orbit. In meas-uring time, Aryabhata determined that thelength of a year is 365 days, six hours, 12 min-utes, 30 seconds, an extremely close calcula-tion to the modern standard of 365 days, sixhours.

Much of his work concerns the Moon.Aryabhata explains the phases of the Moon,which he says result from the shadows of theEarth, and using this same concept of shadowsand the proximity of the Earth, the Sun, and the

Moon, he explains solar and lunar eclipses. Healso determined that the Moon revolves aroundthe Earth. All of Aryabhata’s work was done be-fore the invention of the telescope.

There is an ancient Sanskrit saying thatthere are suns in all directions. Another suggeststhat when our Sun “sinks below the horizon, athousand suns take its place.” It is likely thatAryabhata’s original work led to this very earlyunderstanding by Indian astronomers that ourSun is in fact a star.

Aryabhata’s work was originally written inSanskrit, and Aryabhatiya was finally translatedinto Latin toward the end of the 13th century,making its way to Europe, where its biggest im-pact was on mathematicians. By this time, as-tronomers were already familiar with the workof Copernicus, so Aryabhata’s text was not con-sidered groundbreaking.

In honor of his magnificent original work inthe field of astronomy, the first Indian satellitewas named after him, and a crater on the Mooncarries the name of Aryabhata.

B

31

5 Baade, Wilhelm Heinrich Walter(1893–1960)AmericanAstronomer

German-born American astronomer Walter Baademade a name for himself many times over forhis significant contributions to the understand-ing of the universe. He collaborated with Swissastronomer FRITZ ZWICKY on supernovae andneutron stars, and with Rudolf Leo BernhardMinkowski on radio sources as they pertained toCygnus A and others. But it was taking advan-tage of wartime blackouts and peering intoAndromeda that led to his greatest discoveries,in which he determined through new classifi-cations of stars that the galaxy was twice as bigand twice as old as scientists had previouslyimagined.

Baade was born in Schröttinghausen,Germany, on March 24, 1893. He began hishigher education at the University of Münster,and obtained his Ph.D. in astrophysics fromthe University of Göttingen in 1919. Throughthe 1920s and into the early 1930s, he workedon staff at the Hamburg Observatory where, de-spite the less-than-ideal instruments he had towork with, he began studying comets, starclusters and variable stars, minor planets, andgalaxies.

Soon after beginning work at Hamburg,Baade made his first major discovery, that of anunusual asteroid he named Hidalgo, which hasthe largest known orbit of any asteroid. He hadalready started to get attention from the astro-nomical community, and was invited to theMount Wilson Observatory in California for aone-year visit through a Rockefeller fellowship.Upon his return to Germany, he urged that stud-ies should be done in the Southern Hemisphererather than competing with the United Statesin Northern Hemisphere astronomy. He was par-ticularly interested in studying variable stars.

When Bernhard V. Schmidt (1879–1935),an accomplished optical specialist who made tel-escopic mirrors, joined the staff at Hamburg in1926, Baade made another contribution to thefield. Schmidt joined him in a 1929 expeditionto the Philippines, and Baade suggested that theastronomical community really needed a goodaberration-free wide-field camera. The camerasused at the time were not precise enough forastronomers to make any accurate estimates, inBaade’s opinion. Schmidt set upon the task im-mediately after returning to Hamburg, andcreated the Schmidt camera in 1930, whichultimately replaced all of the old-technologyportrait lenses previously used in astronomy,providing astronomers with clear, sharp imagesfor study.

32 Baade, Wilhelm Heinrich Walter

By 1931 Baade made his next big move. Heleft Hamburg to immigrate to the United States,securing a position at Mount Wilson Observatory.This was the first Carnegie observatory built,and it housed the historic 60-inch reflectingtelescope, which was completed in 1909, plusthe world’s largest telescope, the 100-inch,which was completed in 1918. EDWIN POWELL

HUBBLE had used this telescope to make his dis-covery of the expanding universe. It was herethat Baade peered into the night sky to studyspiral galaxies, especially the AndromedaGalaxy (M31).

Baade’s collaborators over the next severalyears included Swiss astronomer Fritz Zwicky. In1934 the two collaborated on their theories andannounced that neutron stars and cosmic rayswere the result of supernovae.

Baade’s interest in finding the center of theMilky Way Galaxy began in earnest in 1937. Heexpanded his work to include observations ofthe Sculptor and Fornax dwarf galaxies withHubble in 1939, and searched for the central starof the Crab Nebula, which he ultimately identi-fied as having resulted from the supernova of 1054.

By the 1940s Baade discovered a window ofopportunity to gather data on our galaxy. TheMilky Way had proved difficult to penetratebecause it was so obscured by cosmic dust. ButBaade made a discovery near the center of theGalaxy, finding an area, which he called a win-dow, that contained relatively little opaque dust,allowing observers to peer inside. This regioncontains millions of visible stars, and is viewedthrough what is now called Baade’s Window tostudy the composition and design of the MilkyWay. Baade’s interest in spiral galaxies turned to-ward the Andromeda Galaxy.

In 1941 the United States went to war.Many of Baade’s colleagues were helping withthe war effort, but Baade, a German-born im-migrant who had intended to file for U.S. citi-zenship but with his busy schedule and his dis-like of bureaucracy let his papers expire, found

himself prohibited from getting involved in mil-itary research. During World War II, blackoutswere frequent enough in Los Angeles that Baadewas able to use the 100-inch Hooker telescopeto focus on the center of the Andromeda Galaxy.Classified as M31, Andromeda was first recordedby the Persian astronomer Abd-al-Rahman al-Sufi (903–986) who called it “little cloud,” butits discovery was credited to Simon Marius(1573–1624) in 1612 by the French astronomerCHARLES MESSIER, who was the first astronomerto view the galaxy through a telescope, and cat-alogued it as the 31st nonstar object in 1774.Baade became the first astronomer of record tostudy the galaxy.

During his observations, Baade focused hisattention on variable stars, both eruptive vari-ables, and a special kind of pulsating variable—the Cepheid variables. First discovered in1784 by a 19-year-old English astronomer, JohnGoodricke (1764–86), Cepheid variable stars areyellow supergiants that expand and contract ina pulsating fashion. The pulsating is not only anexpansion and contraction of the physical sizeof the star, but also of the star’s brightness or lu-minosity. The time it takes to go through a puls-ing cycle depends on the star’s density—longerfor a giant star with low density, and shorter fora smaller star with high density. The NorthStar, Polaris, is a Cepheid variable that takes alittle less than four days to go through a pulsingcycle.

In 1912 an astronomer at Harvard, HENRIETTA

SWAN LEAVITT, was examining 25 Cepheid vari-ables that she discovered in the Small Mag-ellanic Cloud, and found that there is a rela-tionship between the stars’ luminosity and itsperiod of pulsation—stars that appear to bebrighter have longer periods of light variation.During the same time that Leavitt made her dis-coveries, HARLOW SHAPLEY had concluded thatCepheid variables could be used to calculate dis-tance. Based on his conclusions, Shapley wasinvolved in a famous debate in 1920 with HEBER

Baade, Wilhelm Heinrich Walter 33

DOUST CURTIS over the size of the galaxy, whichat that time was synonymous with the size ofthe universe. The score on this issue was finallysettled some years later by Hubble.

Baade’s work in 1941 allowed him to makea remarkable discovery about the variable starshe saw and expand the ever-evolving ideas aboutthe state of the universe. He realized that therewere two kinds of Cepheid variable stars inAndromeda. The younger, whitish-blue starsfound in the spiral arms he called Population Istars. The older, reddish stars, found in the coreof the galaxy, became known as Population IIstars. During the next decade, Baade was able toidentify more than 300 Cepheid variables, andhe categorized these stars into two types. Thisinformation was significant.

The Cepheid variables in the arms of theAndromeda Galaxy were found to be four timesbrighter than their counterparts. Hubble hadpreviously used only the older stars to estimatethe age of the universe based on the equipmenthe had at the time for observation, and he de-termined that Andromeda was 800,000 light-years away, and the universe was approximately1 billion light-years in size. But with Baade’sdiscovery of two kinds of Cepheid variables,with differing factors of brightness, using bothPopulation I and Population II stars for compu-tations allowed the astronomer to determinethat Andromeda was actually 2 million light-years away. It followed that other galaxies werealso farther away, twice as far as had been orig-inally calculated. Suddenly, the size of the uni-verse had increased by a magnitude of two.And so, too, the age of the galaxy doubled, toapproximately 10 billion years old.

This had an impact back home in theMilky Way. Baade suggested that data aboutAndromeda’s spiral nature could be applied toour own galaxy. And he suggested a search fornew cluster variables in the Magellanic Clouds,which he urged to be studied from the new1.5-meter reflector telescope in Argentina.

Another of Baade’s major discoveries in-volved another type of variable star—the erup-tive variable. This kind of star has an unpre-dictable outburst—or, more rarely, a decrease—inits luminosity. A nova is an eruptive variable.Nova, which means “new,” describes a star that isvery hot and very small. Because of its size, a novahas such a low luminosity that it cannot be seenby the naked eye. It suddenly flares up to thou-sands of times its luminosity, often resulting in ex-ploding fragments of itself hurtling through space.When the star flares up to this kind of brightness,it appears to suddenly burst into the night sky.The ancient Chinese astronomers, called them“guest stars” because they suddenly just show up.

A nova can take years or decades to returnto its original luminosity, and its course can becharted as a light curve. Another eruptive star is the supernova, and it is a far more rarephenomenon than the nova. The most famousare the Supernova of 1054, and Tycho’s Star in1572, viewed in the constellation Cassiopeia bythe Renaissance astronomer TYCHO BRAHE, whonamed it Stella Nova. Baade took a look at an-other star that had appeared to have undergonea nova reaction in 1604 in Serpens, whichJOHANNES KEPLER and GALILEO GALILEI had witnessed. Studying the star’s light curve, andusing the photographic capability of the 100-inch telescope, Baade set out searching for evi-dence and he soon found it in fragments of thestar’s explosion. The discovery made this thethird famous supernova in recorded history.

The next big event came in 1944, againusing the 100-inch reflector. Baade found thecenter of the Andromeda Nebula, and its twocompanion galaxies M32 and NGC205, two ofthe four small cluster galaxies in the spiralAndromeda Galaxy. This was a feat that manywere anticipating with the upcoming completionof the 200-inch telescope, still under construc-tion at Palomar, and one that had been consid-ered impossible with the current equipment. Itwas a major victory for Baade.

34 Barnard, Edward Emerson

Baade’s career came full circle with the dis-covery of another asteroid in 1949. As uniqueas his first, this new asteroid was both an Earth-grazer, because of its close proximity of a mere4,000,000 miles in its orbit from Earth, and anApollo-object, because it passes the Sun by a dis-tance of just 17,700,000 miles during its 1.12year orbit. Baade named this asteroid after theGreek mythic character Icarus, whose wax wingsmelted and cost him his life when he flew tooclose to the Sun.

Prior to 1952, astronomers had argued thatradio sources were coming from distant galaxies.In fact, they were right, but it took Baade, incollaboration with Minkowski, to prove them so.Centaurus A was discovered on August 4, 1826,by James Dunlop (1793–1848) and described indetail in 1849 by SIR JOHN FREDERICK WILLIAM

HERSCHEL, but basically ignored by the astro-nomical community until 1949 when an 80-foot radio antenna erected in Dover Heights,Australia, was used by astronomers John Bolton,G. Stanley, and Bruce Slee, who became the firstto identify it as a radio galaxy. By 1954 Baadeand Minkowski had begun a new project ofsystematically surveying the positions of radiosources with the new 200-inch telescope at thePalomar Observatory. They needed optical iden-tification, and they got it. The two visually con-firmed that Centaurus A was truly a galaxy. Inaddition to making visual identifications of theradio source from this galaxy, they identified oth-ers as well, including Cassiopeia A, Cygnus A,Perseus A, and Virgo A.

Baade was awarded the Royal AstronomicalSociety Gold Medal in 1954, and the prestigiousBruce Medal in 1955. He continued his work atMount Wilson until 1958, and said later that he“greatly regretted” his retirement. Baade’s publi-cations were few, considering the enormous con-tributions he made to science, and this fact wasnoted, and yet accepted, by his colleagues, oneof whom, a former executive at Carnegie Institute,explained that while Baade had published very

little in writing, “he ‘publishes’ his data by con-versations in his office with the world’s as-tronomers,” adding that Baade “is one of themost prolific of our staff.”

After his retirement, Baade went to Australiafor six months and studied the center of theMilky Way on a 74-inch telescope at the MountStromlo Observatory in Canberra. The follow-ing year, he returned to Göttingen to accept aposition as Gauss professor, bringing his astro-nomical career full circle. Plagued with hip trou-ble for many years, Baade underwent surgery totake care of the problem, and died of respira-tory failure, a complication from the surgery, onJune 25, 1960. His work, finally in preparationfor publication, is now in the hands of theMount Wilson, Palomar, and Leiden observato-ries. In honor of his contributions to astronomy,lunar crater Baade was named for him, and theMagellan I telescope has been renamed the WalterBaade Telescope.

5 Barnard, Edward Emerson(1857–1923)AmericanAstronomer

A Nashville, Tennessee, native son born intoextreme poverty, Edward Emerson Barnard ex-celled in astronomy against all odds through hisintelligence, perseverance, and dedication to thefield, and became recognized as one of the great-est astronomers of the late 19th and early 20thcenturies. Gifted with uncanny eyesight, greatphotographic skills, and exceptional powers ofobservation, Barnard discovered 16 comets, amoon, a couple hundred nebulae, some binarystars, and a namesake star, and was a pioneer inastrophotography, using wide-angle photographyto record stars, comets, nebulae, and the MilkyWay. For his extraordinary work and contribu-tions, he gained both fortune and internationalfame during his lifetime.

Barnard, Edward Emerson 35

Barnard was born in Nashville, Tennessee,when the Union army had control of the cityduring the Civil War. His father died before hewas born, leaving Barnard’s mother destitute.Unable to afford schooling for her son, she ed-ucated him herself until he was nine years old,and was finally able to scrimp together enoughmoney to send him to school. But after just twomonths, the depth of their poverty hit home,and with no child labor laws in place, Barnardwas forced to quit school and get a job to helpsupport them. He found work at a photographygallery manning a solar enlarger, a device thattracks the sun to make photographic prints. Hisjob was to manually position the enlarger to keepit pointed directly at the Sun on sunny days.

In 1876 the book The Practical Astronomerwas given to him by a friend as a gift for a favorhe had done, and Barnard was suddenly intro-duced to the field that would become his life’swork. Aided by a coworker, James W. Braid,Barnard built his first telescope out of a card-board tube and a broken glass lens they foundon the street. He later recalled in his writingsthat looking through this homemade telescope“filled my soul with enthusiasm when I detectedthe larger lunar mountains and craters, andcaught a glimpse of one of the moons of Jupiter.”He was inspired enough that he decided to in-vest $380 the following year to buy a five-inchrefracting telescope. This amounted to two-thirds of his entire salary for the year.

Armed with his new investment, Barnardwas presented with another exciting opportunityin 1877, when the American Association for theAdvancement of Science (AAAS) held its an-nual meeting in Nashville. Buoyed by his lovefor the field, an excited Barnard sought out theAAAS president, SIMON NEWCOMB, hoping toget some solid advice on how to become a pro-fessional astronomer. When Newcomb heardthat Barnard had no formal education andno mathematical background, he allegedly toldBarnard that there was no opportunity for him

to make astronomy a profession, and advisedthat he should just stick with it as a hobby. Manyyears later, Barnard confessed that he left themeeting with Newcomb, found a secluded spotbehind the state capitol building, and cried.

Fortunately, he did not heed Newcomb’sadvice. He continued to peer into space, andbegan to record his thoughts about planetaryobservation in 1880 in a little book he wrote,but never published, about Mars. Then camenews about a lucrative, although unconven-tional, way to generate income in astronomy.H. H. Warner, a wealthy astronomy patron fromRochester, New York, announced that he wouldgive $200 to anyone who discovered a newcomet. Barnard jumped at the opportunity, andmade his first new comet discovery through hisfive-inch telescope in 1881. As a newlywed,Barnard used the money from the discovery ofcomet 1881 VI, as it was named, as a down pay-ment to build a house for his bride, RhodaCalvert.

Later that year he was offered a job at theMount Hamilton Lick Observatory, near SanJose, California, taking inventory of the prop-erty. He worked during the day and anticipatedthe opportunity to make important observationswith the big 36-inch telescope at night, forwhich he traveled west. But Edward Holden(1846–1914), the observatory’s director, hadgrand ideas of his own, assigning himself twonights a week on the apparatus while giving twoother astronomers, S. W. Burnham and JamesKeeler, two nights each, leaving one night openfor the public and leaving Barnard out of theloop. If Barnard wanted to do any observations,it would have to be on the 12-inch refractor inthe observatory’s other dome, which he had toshare with the other astronomers, or on his owntelescope.

Holden’s newfound desire for personal fameled him to decide to produce a pictorial atlas ofthe Moon, and he wanted Barnard to helpdevelop his pictures. Upon discovering that

36 Barnard, Edward Emerson

Holden’s pictures were for the most part out offocus and of very poor quality, Barnard insteadrigged up a camera on the observatory’s inex-pensive six-inch telescope and started trackingcomets. His pictures were extremely well fo-cused. In 1892 he made the first photographicdiscovery of a new comet. With such clear pic-tures, he began photographically recording theMilky Way and, as with his early days at thephotography gallery using the solar enlarger, itdemanded that he keep the telescope pointedexactly at its target for hours at a time while ittracked the night sky.

Barnard did get some use out of the 12-inchtelescope at Lick, and began to observe Jupiterthat same year, noting that the moon Io ap-peared to him darker at the poles and lighter atthe equator. This took amazing eyesight andfocused observation to see with such limitedequipment, and it was not until bigger telescopeswere developed in the 1900s that his observationsabout Io were confirmed.

From 1888 to 1892, Barnard did not get touse the 36-inch telescope. But that was about tochange. Holden was alienating the staff, andBurnham decided to leave the observatory.Barnard jumped at the opening on the telescope,asking the regents to let him have the time pre-viously allocated to Burnham. Within threeshort months, in September 1892 Barnard madea discovery that propelled him into instantfame. While looking at Jupiter’s four moons, dis-covered by GALILEO GALILEI in 1610, he foundthat the planet actually had five moons. His dis-covery of Jupiter’s fifth moon, Amalthea, on the36-inch telescope, made him an instantcelebrity. Today, Jupiter is known to have 60moons and is predicted to have 100 or so, themost recent 43 of which were discovered at theUniversity of Hawaii by physics professor DavidC. Jewitt and graduate student Scott S. Sheppard,using the 3.6-meter (approximately 140-inch)Canada-France-Hawaii telescope atop MaunaKea—a far cry from Barnard’s 36-inch variety.

Barnard’s interest in Mars was never far fromhis mind, and in 1892 he had the opportunityto observe it at opposition. But the timing wascursed with poor viewing conditions that meanthe could only use magnifications of 350x or lesson the 36-inch telescope, making it nearly im-possible to record any visual observations.Undaunted, he waited for the next opportunityin 1894, and he began making observations threemonths before opposition, in July. By September,he was using magnifications of 1000x, observingfrom sunset to sunrise, and recording in his notesthat he “failed to see any of Schiaparelli’s canalsas straight narrow lines,” adding that even “un-der the best conditions,” they “could never betaken for the so-called canals.” He was certainthere was nothing artificial on the Martianlandscape.

By 1895, despite his growing public acclaim,Barnard was getting nowhere with Holden. Thepresident refused to publish any of Barnard’sstunning Milky Way photographs, and when thedisillusioned Barnard was presented with an-other opportunity to further his contributions tohis field, he took it. The University of Chicagowas surpassing the Lick Observatory by buildinga 40-inch refracting telescope at the new YerkesObservatory, and they wanted Barnard to jointhem as a professor of practical astronomy.

True to form, Barnard and his wife movedto Chicago nearly a year before the Yerkes ob-servatory was finished, and he began working atthe Kenwood Observatory for GEORGE ELLERY

HALE, who was designated to become the direc-tor at Yerkes. This time, Barnard also had hisportfolio of photographs to work on from theLick Observatory, which he was preparing topublish as an atlas, as well as his continued ob-servations of the Milky Way, comets, and nebu-lae, while he waited for construction of Yerkesto be completed.

In 1897 Barnard and his wife moved toYerkes in Williams Bay, Wisconsin, and he wasjoined on staff by his old colleague Burnham

Barnard, Edward Emerson 37

from the Lick Observatory, where the twoworked with Hale to compare observationsbetween the Yerkes 40-inch refractor and the36-inch from Lick. During their tests, Barnard’sobservational skills, coupled with the greatpower of the new telescope, led to his discoverythat Vega was actually a double star.

In May Barnard and Hale’s assistantFerdinand Ellerman were scheduled to observenebulae one evening using the 40-inch refrac-tor. At around 12:45 A.M., the men heard a noisewhen they raised the elevated floor, but theycould not figure out the source of the sound.After two and a half hours of observation,Barnard uncharacteristically cut short his typi-cal all-night observation. Soon after the twomen left the building, the 371⁄2-ton floor’s sup-porting cable broke, and the floor crashed to theground, exploding into a heap of rubble.

Burning with a passion to collect the bestphotographic data of the galaxy, Barnard so-licited a $7,000 grant in 1897 from another NewYork astronomy patron, Catherine W. Bruce(1816–1900). With Bruce’s gift, Barnard over-saw the creation of a new five-inch telescopeon which he had mounted two photographicdoublets of a 61⁄4-inch and 10-inch aperture.Barnard’s unbending determination in gettingthe widest photographic field and the shortestrelative focus caused multiple delays in the com-pletion of the telescope, which took until 1904.In the meantime, he continued observationsthroughout the night at Yerkes, sometimes to hisown detriment in the cold Wisconsin winters.Barnard was known for getting completely lostin his work, so it was not too surprising whenone particularly cold Wisconsin night he didnot realize that his nose had frozen stuck to theeyepiece of the telescope.

By the time the new Bruce five-inch pho-tographic telescope was finally completed in1904, a small wooden observatory with a 15-footdome was built for it near Barnard’s home. Soon,Hale wanted to put the telescope to use on solar

research he was overseeing at the Mount WilsonObservatory in California, so the telescope, andBarnard, were shipped to California for severalmonths to gather visual data that was not pos-sible at the altitudes at Yerkes. Here, Barnardcontinued his photographic discovery of theMilky Way for about seven months beforereturning to Wisconsin.

In May 1916, while looking at a new pho-tographic plate he had taken, Barnard discovereda star that he could not find when he comparedit to another plate he took in August of 1894.However, there was a star at a different locationon the 1894 plate that was not on the 1916 plate.He compared the two to a third plate taken in1904, and found that neither star was on the1904 plate, but there was another star that waslocated about half the distance between the two.Barnard had discovered a new star. A red dwarf,Barnard’s Star has the largest proper motion ofany known star, at 10.3 arcsecond per year ascompared to the typical rate of about 1 arcsec-ond, and is the fourth closest star to our system,after the three Alpha Centauri stars, at 1.821parsecs.

Barnard spent a total of 28 years at Yerkes,lecturing, researching, photographing, and writ-ing. In 1897 the Royal Astronomical Society ofGreat Britain awarded him the gold medal forhis photographic work with the six-inch tele-scope at Lick. In 1917 he was awarded the BruceMedal. He is the only faculty member atVanderbilt University to have a building namedafter him, and after his death in 1923, theBarnard Astronomical Society was founded inhis honor in Chattanooga, Tennessee. His homeat Yerkes was deeded to the university upon hiswife’s death, and it remains today as the resi-dence of the director of the observatory.

Barnard discovered nearly 200 nebulae inhis lifetime, published more than 900 articles,and created more than 4,000 photographicplates of the Milky Way. He was the first todiscover a comet with photography, and the

38 al-Battani

last to discover a moon visually. His life’s work,Photographic Atlas of Selected Regions of the MilkyWay, was published after his death by theUniversity of Chicago Press. His belief thatsleep was a complete waste of time, along withhis dedication to observation, earned him thetitle as the man who never sleeps, and he wasuniversally recognized as one of the greatest andmost prolific observers ever to work in the fieldof astronomy.

5 al-Battani (Abu Abdullah Mohammad ibn Jabir ibn Sinan al-Raqqi al-Harrani al-Sabi al-Battani, Albategnius)(ca. 858–929)ArabAstronomer, Mathematician

Al-Battani (Latinized name: Albategnius) isregarded as the best and most famous astronomerof medieval Islam. As a skilled naked-eye ob-server he refined the sets of solar, lunar, and plan-etary motion data found in PTOLEMY’s great work,The Almagest, with more accurate measurements.Centuries after his death, these improved obser-vations, as contained in his compendium, Kitabal-Zij, worked their way into the Renaissanceand exerted influence on many western Europeanastronomers and astrologers alike. Al-Battaniand his fellow Muslim stargazers preserved andrefined the geocentric cosmology of the earlyGreeks.

Though al-Battani was a devout follower ofPtolemy’s geocentric cosmology, his precise ob-servational data encouraged NICOLAS COPERNICUS

to pursue heliocentric cosmology—the stimulusfor the great scientific revolution of the 16th and17th centuries. Al-Battani was also an innova-tive mathematician who introduced the use oftrigonometry in observational astronomy. In880 he produced a major star catalog (the Kitabal-Zij) and refined the length of the year toapproximately 365.24 days.

Al-Battani was born in about 858, in theancient town of Harran, located in northernMesopotamia some 44 kilometers southeast ofthe modern Turkish city of Anliufra. His fullArab name is Abu Abdullah Mohammad ibnJabir ibn Sinan al-Raqqi al-Harrani al-Sabial-Battani, which later European medievalscholars who wrote exclusively in Latin changedto Albategnius. His father, Jabir ibn Sinan al-Harrani, was an astronomical instrument makerand a member of the Sabian sect, a religiousgroup of star worshippers in Harran. So al-Battani’s lifelong interest in astronomy probablystarted at his father’s knee in early childhood.Al-Battani’s contributions to astronomy are bestappreciated within the context of history. At thistime, Islamic armies were spreading throughEgypt and Syria and westward along the shoresof the Mediterranean Sea. Muslim conquests inthe eastern Mediterranean resulted in the cap-ture of ancient libraries, such as the famous onein Alexandria, Egypt. Ruling caliphs began torecognize the value of many of these ancientmanuscripts and so they ordered Arab scribes totranslate any ancient document that came intotheir possession.

By fortunate circumstance, while the RomanEmpire was starting to collapse in westernEurope, Nestorian Christians busied themselvespreserving and archiving Syrian-language trans-lations of many early Greek books. CaliphHarun al-Rashid ordered his scribes to purchaseall available translations of these Greek manu-scripts. His son and successor, Caliph al-Ma’mun, who ruled between 813 and 833, wenta step beyond. As part of his peace treaty withthe Byzantine emperor, Caliph al-Ma’mun wasto receive a number of early Greek manuscriptsannually.

One of these tribute books turned out tobe Ptolemy’s great synthesis of ancient Greekastronomical learning. When translated, it be-came widely known by its Arabic name, TheAlmagest (or “the greatness”). So the legacy of

al-Battani 39

geocentric cosmology from ancient Greecenarrowly survived the collapse of the RomanEmpire and the ensuing Dark Ages in westernEurope by taking refuge in the great astronomi-cal observatories of medieval Islam as found inBaghdad, Damascus, and elsewhere.

But Arab astronomers, like al-Battani, didnot just accept the astronomical data presentedby Ptolemy. They busied themselves checkingthese earlier observations and often made im-portant refinements using improved instruments,including the astrolabe, and more sophisticatedmathematics. History indicates that al-Battaniwas a far better observer than any of his con-temporaries. Yet, collectively these Arab astro-nomers participated in a golden era of naked-eyeastronomy enhanced by the influx of ancientGreek knowledge, mathematical concepts fromIndia, and religious needs. For example, Arab as-tronomers refined solar methods of timekeepingso Islamic clergymen would know precisely whento call the faithful to daily prayer.

Al-Battani worked mainly in ar-Raqqah,and also in Antioch (both now located in mod-ern Syria). Ar-Raqqah was an ancient Romancity along the Euphrates River, just west of whereit joins the Balikh River at Harran. Like otherArab astronomers, he essentially followed thewritings of Ptolemy and devoted himself to re-fining and improving the data contained in TheAlmagest. While following this approach, hemade a very important discovery concerning themotion of the aphelion point—that is, the pointat which Earth is farthest from the Sun in its an-nual orbit. He noticed that the position at whichthe apparent diameter of the Sun appearedsmallest was no longer located where Ptolemysaid it should be with respect to the fixed starsof the ancient Greek zodiac. Al-Battani’s datawere precise, so he definitely encountered a sig-nificant discrepancy with the observations ofPtolemy and early Greek astronomers. But nei-ther al-Battani nor any other astronomer whoadhered to Ptolemy’s geocentric cosmology could

explain the physics behind this discrepancy. Theywould first need to use heliocentric cosmologyto appreciate why the Sun’s apparent (measured)diameter kept changing throughout the year asEarth traveled along its slightly eccentric orbitaround the Sun. Second, the Sun’s annual ap-parent journey through the signs of the zodiaccorresponded to positions noted by the earlyGreek astronomers. But because of the phe-nomenon of precession (the subtle wobbling ofEarth’s spin axis), this correspondence no longertook place in al-Battani’s time—nor does it to-day. As al-Battani looked out from Earth, henoticed that when the Sun’s apparent diameterwas smallest, it did not occur where the greatstar master Ptolemy said it was supposed to. Butwithout the benefit of a wobbling Earth model(to explain precession) and heliocentric cos-mology (to explain the variation in the Sun’sapparent diameter) it was clearly impossible forhim, or any other follower of Ptolemy, to appre-ciate the true scientific significance of what hediscovered.

Al-Battani’s precise observations also al-lowed him to improve Ptolemy’s measurementof the obliquity of the ecliptic—that is, the an-gle between Earth’s equator and the plane de-fined by the apparent annual path of the Sunagainst fixed star background. He also madecareful measurements of when the vernal andautumnal equinoxes took place. These observa-tions allowed him to determine the length of ayear to be about 365.24 days. The accuracy ofal-Battani’s work helped the German Jesuitmathematician Christopher Clavius (1537–1612)reform the Julian calendar and allowed PopeGregory XIII (1502–85) to replace it in 1582with the new Gregorian calendar that nowserves much of the world as the internationalcivil calendar.

While al-Battani was making his astronom-ical observations between the years 878 and918, he became interested in some of the newmathematical concepts other Arab scholars

40 Bayer, Johannes

were discovering in India. Perhaps al-Battani’sgreatest contribution to Arab astronomy was hisintroduction of the use of trigonometry, espe-cially spherical trigonometric functions, to re-place Ptolemy’s geometrical methods of calcu-lating celestial positions. This contributionallowed Muslim astronomers to use some of themost complicated mathematics known in theworld up to that time.

Al-Battani died in 929 in Qar al-Jiss (nowin modern Iraq) on a homeward journey fromBaghdad. His contributions to astronomy con-tinued for many centuries after his death. Forexample, medieval astronomers became quitefamiliar with Albategnius, primarily through a12th-century Latin translation of his Kitab al-Zij, renamed De motu stellarum (On stellarmotion). The invention of the printing press in 1436 by Johann Gutenberg soon made itpractical to publish and widely circulate theLatin translation. This occurred in 1537 inNuremberg, Germany—just in time for thecenturies-old precise observations of al-Battanito spark interest in some of the puzzling astro-nomical questions that spawned the scientificrevolution.

5 Bayer, Johannes (Johann)(1572–1625)GermanLawyer, Astronomer (Amateur)

For a man whose work in astronomy was con-ducted purely as a hobby while he made his liv-ing as a lawyer, the Bavarian-born Johann Bayermade one of the most important contributionsto the field of astronomy when he published hisstar atlas, Uranometria.

Little is known about Bayer’s early life. Hisformal education began with an interest inphilosophy at the university in Ingolstadt,Germany, but he switched schools and changedhis focus to study law at Augsburg, where he

eventually became a lawyer and the city’s legaladviser. As analytical as his chosen professionwas, his interest in astronomy allowed him tointegrate both his analytical mind and his aes-thetic talents, as evidenced by his artistic andmeticulously accurate book.

Printed in 1603 by the 31-year-old Bayer,Uranometria was considered the first modern at-las of the constellations. Devised to give as-tronomers a precise guide to the stars, his atlaswas a combination of beautiful plates of the con-stellations plus technical data regarding their po-sitions and brightness.

The atlas included many firsts. Instead ofusing PTOLEMY’s original 48 constellations, Bayerused the star calculations compiled by TYCHO

BRAHE and JOHANNES KEPLER, which they hadpublished only one year prior to Bayer’s book,and which included more than 700 stars.Uranometria was also the first book to includethe 12 new Southern Hemisphere constellationsof Apus, Chamaeleon, Dorado, Grus, Hydrus,Indus, Musca (also called Apis), Pavo, Phoenix,Triangulum Australe, Tucana, and Volans, orig-inally discovered and catalogued by the 16th-century Dutch navigator Pietr Dirksz Keyser.The book took a new artistic path as well. Ratherthan using woodcuts, the star maps were doneas large, detailed engravings. And despite thefact that they were presented as beautiful art,Bayer never lost sight of the fact that the platesand the accompanying tables were first andforemost meant to be accurate maps.

The most important feature of Bayer’s atlaswas the system he created to name and classifythe stars, using lowercase Greek letters followedby the plural Latin name of the constellation.He designated the brightest star of a constella-tion with the first letter in the Greek alphabet,making it the alpha star. The remaining lettersof the Greek alphabet were used in decreasingorder to indicate each star’s brightness within aconstellation, making the brightest star alpha,the second brightest beta, and so on. Under this

Beg, Muhammed Taragai Ulugh 41

system, the brightest star in the constellationCentaurus became Alpha Centauri. This nomen-clature was printed in tables, along with de-scriptions and positions of the stars, used inconjunction with the engraved charts.

Bayer’s classifications were modified some-what in 1725, when the British astronomer JohnFlamsteed created a numbering system that indi-cated a star’s position from west to east. In 1774CHARLES MESSIER expanded on and devised hisown system when he began cataloging nebulaeand galaxies. And in 1843 FRIEDRICH WILHELM

AUGUST ARGELANDER released Uranometria Nova,a new, updated version of the atlas, in homageto the work done by Bayer nearly two and halfcenturies earlier.

The International Astronomical Union,founded in 1919, picked up where Bayer and hissuccessors left off, regulating star classificationsas more and more stars become visible with theaid of modern technology. For his contributionthrough Uranometria, Bayer’s work became thefoundation of today’s star classifications, and thestandard to which star atlases have been held formore than 400 years.

5 Beg, Muhammed Taragai Ulugh(ca. 1393–1449)PersianMathematician, Astronomer

The mathematician and astronomer Ulugh Begwas by birthright a Persian prince, son of ShahRukh, and grandson of the Mongol conquerorTimur, who amassed a great empire, includingparts of modern-day Iran, Iraq, Turkey, Syria, andIndia. Married around age 10, Beg tended to hisprincely duties under his father’s rule, and be-came even more active in his role after his grand-father’s death in battle in 1405. In 1409 ShahRukh moved the seat of his empire to present-day western Afghanistan, and set out to makethe chosen city of Herat a cultural, educational,

and trading capital. When Beg was 16, his fatherturned over leadership of the Mawaraunnahrregion to him, giving him control of, amongother cities, Samarkand.

The learned Beg was a gifted poet andhistorian, and a Hafiz, one who could recite theQur’an by heart. But despite the legacy left byhis grandfather, Beg was not afflicted with adesire to conquer. Instead, his intentions wereto further the study of science, particularlymathematics and astronomy.

Beg’s interest in astronomy reportedly cameabout from a visit to the ruins of the Maraghehobservatory, the workplace of the famous as-tronomer Nas ir al-Din Tusi (1201–74), whoauthored nearly 150 books and translated thegreat works of the ancients, including Archimedes,Euclid, and PTOLEMY. In 1271 al-Tusi wrote theZij-i Ilkhani, also known as the famous IlkhanTablets, a compilation of tables of planetaryorbits.

In pursuit of his desire to turn Samarkandinto a leading educational center, Beg orderedthe building of a madrasah, an institution forhigher learning, in 1417. When constructionwas completed in 1420, the facilities openedwith approximately 70 of the leading scientistsof the day participating in the most advancedresearch, observations, discussions, and lectures.Surrounded by great minds, and an accom-plished astronomer in his own right, Beg’s visionfor furthering scientific study grew into a planto build a massive observatory. In 1428 con-struction began on a great circular building thatwas three stories high and more than 50 metersin diameter. The combination of the huge ob-servatory and the brilliant minds working atthe madrasah on important observations madeSamarkand the world capital for major astro-nomical study at the time.

Beg was the first in recorded history todevelop the concept of permanently mountingastronomical instruments in a building. His ob-servatory included an armillary sphere, a device

42 Bell Burnell, Susan Jocelyn

that consisted of spherical rings used to modelthe shapes and positions of celestial spheresand to help identify the position of the stars; amarble sextant, known as the Fakhri sextant, forobserving stars and planets and measuring theirdeclinations; and a quadrant that measured stel-lar and planetary altitudes. The quadrant was somassive that the ground had to be excavated tobring the piece of equipment into the buildingfor installation.

Inspired, perhaps, by the writings of al-Tusi,Beg is also credited with the creation of his ownzij, which is an astronomical compilation con-taining tables for calculating current positionsand predicting the future positions of celestialbodies. Beg’s Zij-i Sultani (Catalog of the stars),was published in 1437, and included the namesand positions of approximately 1,000 stars (thereported number varies from 992 to 1,018 to1,022), plus calendar information, an explana-tion of the methods and uses of astronomical ob-servations, a description of the movements ofthe Sun, the Moon, and the planets, a treatiseon astrology, and trigonometry tables of sinesand tangents that are accurate to eight decimalplaces. Beg calculated the length of a year as 365days, five hours, 49 minutes, 15 seconds—lessthan one minute off today’s measurement.

Beg’s Zij was the first major star compila-tion since Ptolemy’s work around the year 170.And despite the fact that it preceded TYCHO

BRAHE’s work, and the invention of the tele-scope, by approximately 200 years, it remainedunknown in Europe until some 50 years afterBrahe’s publications, which were so accuratethat they made the discovery of Beg’s writingsinconsequential.

Leadership of the family’s empire defaultedto Beg in 1447 when his father died. In such apolitical position, the scholarly Beg soon becamevictim to another family member who had aspi-rations of conquest. Beg’s son, ‘Abd al-Latif,secured the services of an assassin and had hisfather murdered by beheading in 1449.

After Beg’s death the city of Samarkandeventually lost its status as a leading educationalcenter. The observatory fell to ruins and was leftvirtually untouched until excavated by Russianarchaeologists in 1908. Beg’s fully-clothed bodywas discovered in 1941 in a mausoleum inSamarkand, buried at the foot of his grandfather’stomb. The importance of the clothing indicatesthat Beg’s people considered him a martyr.

Today, the observatory at Samarkand is anarchaeological site consisting of the building’sfoundation and part of the sextant, plus a smallmuseum in honor of Beg. Using the Latin spellingof his name, the lunar crater Ulugh Beigh hasbeen named in his honor.

5 Bell Burnell, Susan Jocelyn(1943– )IrishRadio Astronomer, Astrophysicist

Born and raised in Belfast, Northern Ireland,near the Armagh Observatory, Jocelyn Bell tookan interest in astronomy during her early teenageyears. As an accomplished astronomer, Bell isknown for her discovery of “little green men”(or LGM, as she nicknamed them), more com-monly known as pulsars.

Bell’s family strongly encouraged her as ayoung girl to study her field of choice, and shehad access to the observatory in part because ofher proximity to it, and in part because her fa-ther, an architect, had designed it. She lived ina very literate household, and was serious abouteducation, although she did not pass entrance ex-ams to get into the British university she wantedto attend, and ended up attending a boardingschool before starting her university education.

Encouraged by radio astronomer ProfessorBernard Lovell, Bell took up physics and becamethe only woman in her class of 50 at theUniversity of Glasgow, from which she graduatedwith a physics degree in 1965. She immediately

Bell Burnell, Susan Jocelyn 43

went to Cambridge University to start workingon her Ph.D., and she immersed herself in build-ing an 81.5-megahertz radio telescope designedto track quasi-stellar radio sources, or quasars.The intent of the project was to significantly im-prove research in the field of radio astronomy,which originally began as a field of study in the1950s. To that end, this new radio telescope wasmassive, using more than four and a half acresof cabling and wires to connect thousands ofnine-foot poles.

With the telescope’s construction com-pleted in July 1967, Bell’s task turned towardthat of a research student, operating the tele-scope and analyzing the data at the university’sMullard Radio Astronomy Laboratory. The ra-dio waves, which turned into signals once theyhit the telescope, were recorded on chart paperevery four hours, spewing out 121.8 meters’worth of paper, nearly 400 feet, every four days,all of which had to be carefully studied and an-alyzed by hand. Within a few months, theNovember analysis showed something different.Bell noticed some glitches in a length of datathat took up just 2.5 centimeters, or just underan inch. Uncertain about what she was seeing,she thought the unusual signal might be “scruff,”as she called it, some sort of cosmic interference.She made notes and waited.

The signals occurred again a few weeks later,and it soon became clear that she was seeingsome very regular patterns: a series of fast pulsesoccurring exactly every 1.337 seconds, originat-ing from outside of our solar system. Excitementover the discovery fueled the imagination of theentire research group, and soon speculation wasrampant throughout the astronomical commu-nity that the signal might be from beaconsdeveloped by extraterrestrials, instantly givingteeth to the theory of intelligent life elsewherein the universe. Bell named the signal LittleGreen Men (LGM) and waited some more.

As the weeks went on, more signals oc-curred, this time from other areas in the galaxy,

and the theory about extraterrestrial life fizzledbased on the probability of the science. Oddswere decidedly against multiple civilizationssending the same signal at the same frequencyat the same time to the same planet. Plus, whenBell recognized that the source changed at a ratevery similar to the rate of the movement of thestars, it became clear that these signals were notartificially manufactured; in fact, they had to benaturally occurring phenomena.

Further research proved that the radio wavesemulated from a special kind of rapidly spinningneutron star, the dense result of an exploding star.The stars, named pulsars, for “pulsating radiostars,” emit signals much like beams of light froma lighthouse beacon sweeping across the nightsky. Only in this case, they are electromagneticradiation combined with radio waves pulsingthrough space in regular bursts as they are thrownoff the rapidly spinning stars. The original pul-sar, dubbed LGM, was officially named CP(Cambridge Pulsar) 1919. Due to naming stan-dards, the opportunity to designate this newlydiscovered star as Bell’s Star, as had been theprecedent in previous centuries, was completelyout of the question. Additional pulsars were soondiscovered by Bell, but the first one was, ofcourse, the most important discovery in thisnewly expanded field of radio astronomy.

For Bell’s work, her thesis adviser atCambridge University, ANTONY HEWISH, re-ceived the Nobel Prize in physics in 1974, thefirst time the award was given for a discovery inthe field of astronomy. Controversy was on theheels of the Nobel announcement, since the dis-covery had clearly been made by the hard workand dedication of Jocelyn Bell. But researchstudents typically do not get Nobel prizes—their professors do. Bell graciously accepted herfate, stating that giving it to a student could“demean” the prize.

Bell received her Ph.D. from Cambridge in1968, married Martin Burnell that same year,and moved to the University of Southampton

44 Bessel, Friedrich Wilhelm

to begin work on gamma-ray research, whereshe stayed until 1973. During her time atSouthampton, she was elected to the RoyalAstronomical Society in 1969, and eventuallyserved as vice president of the organization. In1973 she moved to the Mullard Space ScienceLaboratory at University College in London towork on X-ray astronomy. Nearly a decade later,in 1982, she took a position to focus on infraredand optical astronomy, heading the James ClerkMaxwell Telescope project in Hawaii for theRoyal Observatory in Edinburgh.

Despite the Nobel Prize incident in 1974,Bell Burnell received many awards for her ac-complishments in later years. She was awardedthe Beatrice M. Tinsley Prize in 1987 by theAmerican Astronomical Society and the HerschelMedal from the Royal Astronomical Society in1989. She redirected her career in 1991 to be-come a physics professor and department head atOpen University in Milton Keynes, England. Shewon the Edinburgh Medal in 1999, and took aleave from Open University to work as a distin-guished visiting professor at Princeton Universityin 1999 and 2000. In October 2001 she acceptedthe position of dean of science at the Universityof Bath, England. In addition to her other kudos,Bell Burnell is the recipient of the OppenheimerPrize, the Michelson Medal, the Tinsley Prize, andthe Megallanic Premium Award. She has receivedhonorary doctorates from universities all over theworld, and dedicates a portion of her time to fur-thering women’s study of physics.

5 Bessel, Friedrich Wilhelm(Wilhelm Bessel)(1784–1846)GermanAstronomer

It is often difficult to know the exact event thatcauses someone to head his life in a certain di-rection. But in the case of Friedrich Wilhelm

Bessel, the credit clearly goes to physicianHEINRICH WILHELM MATTHÄUS OLBERS, an am-ateur astronomer who encouraged the youngBessel to develop a career devoted to astronomy.The resulting good fortune for the field of as-tronomy was the introduction of Bessel func-tions, the discovery of the proper motion andlocation of more than 50,000 stars, and the firstaccurate measurement of the distance to thestars.

Bessel began his life in Minden, Westphalia(now part of Germany), living a modest life asone of nine children of Carl Friedrich Bessel, agovernment employee, and Friederike ErnestineSchrader, a pastor’s daughter. His childhood ed-ucation was a brief one at the Gymnasium inMinden, where after four years, at the age of 14,the uninspired student quit school to work as anunpaid accounting apprentice for an import-ex-port business in the town of Bremen. This firstjob proved to be valuable for Bessel because itintroduced him to the world at large, and as hisinterest in other countries grew, so did his mo-tivation to learn about them. Within a few shortyears, Bessel taught himself geography, English,Latin, Spanish, and mathematics, and he beganto study astronomy as a by-product of his inter-est in navigation. At some point during his stud-ies, Bessel ran across calculations on Halley’sComet made by the British mathematician andastronomer Thomas Harriot (1560–1621), whoobserved the comet on September 17, 1607—just seven days after JOHANNES KEPLER made hisobservation. Using Harriot’s data, Bessel recal-culated the comet’s orbit and sent his informa-tion to Olbers, who was considered somethingof an expert on comets despite his amateur sta-tus in the field.

Olbers responded with praise and encour-agement, asking Bessel to do more—make obser-vations, do more detailed calculations—gentlypushing the 20-year-old to create a high-qualitypaper worthy of publishing. He also put Besselin communication with the noted mathematician

Bessel, Friedrich Wilhelm 45

Johann Gauss (1777–1855), and the two devel-oped a relationship that lasted throughoutBessel’s life. When Bessel finally sent Olbers hiscompleted work, Olbers recognized that the im-pressive paper would have earned Bessel aPh.D. if he were in a formal university setting,and he advised Bessel to pursue astronomy as aprofession.

The opportunity arose for Bessel to do justthat in 1806, when a job was offered to him asassistant director at the private LilenthalObservatory near Bremen, owned by Germanastronomer Johann Schroter (1745–1816). Butseven years with the import-export firm hadgiven him a sense of security, not to mention adecent salary, and Bessel had to weigh giving uphis well-paying job for one that paid next tonothing, yet was in the field he loved. Whetherit was his youth or his passion that swayed hisdecision is unknown, but Bessel left the import-export business and never looked back.

Bessel’s first order of business in his newcareer was to learn the art of observation, whichhe did through an expertly crafted seven-foottelescope built by SIR WILLIAM HERSCHEL. Hewas given the task, and the opportunity, to fo-cus his observations on the planet, rings, andsatellites of Saturn, and he continued observingcomets, which always fascinated him. While ad-vancing his observational skills, he devotedtime to furthering his knowledge of celestialmechanics, a field derived from SIR ISAAC

NEWTON’s laws of motion.In 1807 Bessell began delving into the

work of the third Astronomer Royal, ReverendJAMES BRADLEY, whose more than 60,000 ob-servations of heavenly bodies, made between1748 and 1762, were published in two volumesin 1798 and 1805, over a quarter of a centuryafter his death. Star by star, Bessell worked onidentifying the precise locations of more than3,000 stars as they appeared in 1755. As wordgot out about his work, he was offered posi-tions at both the Greifswald and Leipzig ob-

servatories, but he chose to stay at Lilenthaluntil an offer came around that he could notrefuse.

In 1809 Prussia’s King Frederick WilliamIII (1770–1840) ordered the building of a newobservatory in Königsberg (now Kaliningrad,Russia), and the position of director was offeredto the 26-year-old Bessel, along with the roleof teaching astronomy at Albertus University.However, the uneducated Bessel needed a doc-torate to teach at the university level, so his fa-mous friend and colleague Gauss offered hiswhole-hearted recommendation, and Besselwas granted a Ph.D. on the basis of his previ-ous work from the university at Göttingen.With the observatory still under construction,Bessel moved to Königsberg in May 1810 andhis career in his new home was officiallylaunched when he began teaching classes thatsummer. Bessel stayed in Königsberg for the restof his life.

The year 1812 marked two milestones inBessel’s life—he married Johanna Hangen, withwhom he would have four children, and he waselected to the Berlin Academy of Sciences. Hismonumental task of working on Bradley’s obser-vations took a great deal of time, but the fol-lowing year he would become internationallyrenowned for undertaking such an extraordinaryventure.

In 1813 the observatory was finally ready,and Bessel began his job as director. His timingto leave the Lilenthal Observatory proved to bevery fortunate. King Frederick William III’s de-cision in 1806 to start a war with France, in-voking the wrath of the emperor NapoleonBonaparte (1769–1821), resulted in an attackthat divided his country. In the fray, the Frenchmarched into Schroter’s observatory and com-pletely destroyed it and everything inside.Stricken by the loss, Schroter died of apparentagony two years later, in 1815—the same yearBessel was honored for his work by the BerlinAcademy.

46 Bessel, Friedrich Wilhelm

In 1817 Bessel started working on the prob-lem of planetary perturbations—changes intheir orbits—and devised a new class of math-ematical functions called cylindrical functions,more commonly known as Bessel functions.This type of analysis ultimately had a widerapplication than working on planetary pertur-bations, and is now used in hydrodynamics andwave theory, as well as in applied mathematicsand engineering.

The overwhelming task of defining Bradley’swork was finally realized in 1818, when Besselpublished Fundamentae Astronomiae pro AnnoMDCCLV deducta ex Observationibus viri incom-parabilis James Bradley (Foundations of astron-omy for the year 1755, deduced from the ob-servations of the incomparable man JamesBradley). Written in Latin, the work was a thor-ough compilation of the positions of 3,222 stars,including proper motion and spherical astron-omy theory.

Bessel seemed to enjoy delving into thework of the royal astronomers. Perhaps it washis induction into the Royal Society in 1825that sparked an interest in the work of theAstronomer Royal Nevil Maskelyne (1732–1811),and his “fundamental stars.” In 1830 Bessel pub-lished his work on 38 stars, of which 36 werefundamental stars and the remaining two werepolar stars, giving their mean and apparent po-sitions as they appeared between 1750 and1850. While Bessel worked on this production,he became particularly interested in two ofMaskelyne’s stars, Sirius and Procyon. He wouldreturn to these two stars in another 14 years andachieve another milestone in his field.

But first, he returned to one of his favoritesubjects—comets. After all, it was now 1835,and Halley’s Comet, which was responsible forgetting him started in astronomy in the firstplace, was swinging back around in its 76-yearorbit, and Bessel would have the good fortuneof being able to observe it. In 1836 he publishedhis observations in Physical Theory of Comets.

The first official star catalog, credited toPTOLEMY in the second century, consisted ofmore than 1,000 stars and was used until the17th century. Bessel’s undertaking was somewhatlarger than Ptolemy’s, creating a star catalog thatwould have the proper motions and positions ofmore than 50,000 stars. The resulting catalog of75,011 stars would be completed by Bessel’s stu-dent FRIEDRICH WILHELM AUGUST ARGELANDER,and named Bonner Durchmusterung.

While working on this extraordinary task ofcataloging, Bessel focused his attention on 61Cygni. Since this star had the greatest propermotion of any star he knew, Bessel (correctly)thought it might mean that the star was rela-tively close to the planet. He wanted to knowexactly how close.

Accurately measuring the distance to a starwas something that had never been accom-plished, and was in fact a task that seemed tobaffle the scientific community. In order tomeasure the distance, the star needed to be ob-served from two different locations, and a trian-gle formed between the two points of measure-ment and the star. The problem had been thatthere were no two places on Earth that were farenough apart to set up a usable triangulation tothe star. Bessel came up with the brilliant ideaof observing the star from one place on Earthwhen the Earth was in two different locations—along its path as it rotated around the Sun—taking calculations of the stars position every sixmonths, which he did for three years.

This measurement of looking at an objectfrom two different views, and creating a trian-gle connecting the points of view and the ob-ject, is called parallax. In 1838 Bessel an-nounced that he had determined the distanceto 61 Cygni using parallax, becoming the firstastronomer to measure the parallax of a star, tosee the motion of a star due to its parallax, andto calculate the distance to a star. The star 61Cygni, located in the constellation Cygnus theSwan, was declared to be 10.3 light-years away—

Bethe, Hans Albrecht 47

remarkably close to current calculations of 11.2light-years, or 219,072,000,000 miles, fromEarth. In 1841 his accomplishment was offi-cially recognized, and SIR JOHN FREDERICK

WILLIAM HERSCHEL congratulated him on “thegreatest and most glorious triumph which prac-tical astronomy has ever witnessed.” Bessel wasconsequently awarded the Gold Medal by theRoyal Society.

Now it was time to return his attention toSirius. Bessel noticed that there were inequali-ties in the orbits of the two Dog Stars, Siriusand Procyon. After studying them at greatlength, he felt he had figured out the reasonwhy. In 1844 he announced that their propermotions were off because they each revolvedaround another object that could not be seenbut which had a mass similar to that of the Sun.This hypothesis became known as “astronomyof the invisible,” and was an important breakfrom traditional astronomy, which relied uponvisible observations. Bessel was proved correctin his theory when companion stars were dis-covered for Sirius in 1682 by ALVAN GRAHAM

CLARK while he tested an 18-inch refractor tel-escope, and for Procyon in 1896, by JohnSchaeberle (1853–1924) using the 36-inch Lickrefractor. This gave Bessel the distinction of be-ing the first astronomer to predict the existenceof “dark stars,” which in this case turned out tobe white dwarf stars.

Bessel was dedicated to the Königsberg ob-servatory from its inception through the endof his life, forsaking all offers from competitiveobservatories, including the University ofBerlin. He left on a scientific trip in 1842 toattend the Congress of the British Associationin England, where he at long last met manyof the most famous scientists of his time. Thetrip inspired him to do more publishing, andhe published Astronomische Untersuchungen(Astronomical observations) that same year.After six years of declining health, Bessel diedof cancer in 1846.

Bessel made numerous contributions toastronomy and science, and was deservedly awar-ded memberships in a variety of prestigious or-ganizations, including the Royal AstronomicalSociety, the Royal Meteorological Society, theBerlin Academy, Palermo Academy, StockholmAcademy, and others. A star atlas, AkademischeSternkarten (Academic star maps), inspired byBessel, was completed 13 years after his death,in 1859, through the collaboration of a numberof observatories. In 1935 a lunar crater wasnamed Bessel in his honor, and in 1938 anasteroid was given his name.

5 Bethe, Hans Albrecht(1906– )AmericanAstrophysicist

The scientist who answered the question “Wheredo stars get their energy?” is Hans AlbrechtBethe, born on July 2, 1906, in Strassburg,Germany (now Strasbourg, Alsace-Lorraine,France). The son of a psychologist, Bethe startedschool at the age of nine, attending theGymnasium in Frankfurt until 1924, then intohigher education at the University of Frankfurt,where he started his studies in physics. Aftertwo years, Bethe transferred to Munich, andin July 1928 earned his Ph.D. in theoreticalphysics under the expert tutelage of ArnoldSommerfeld, a good friend of ALBERT EINSTEIN.

Bethe immediately began teaching afterMunich—first at the University of Frankfurt,where he taught for one term, then on to theUniversity of Stuttgart, also for just one termuntil he obtained a teaching position in fall1929 at the University of Munich. By thefollowing May, Bethe was promoted to aPrivatdozent (lecturer), and given a fellowshipto travel by the International Education Board.He wasted no time in setting out for Cambridgein the fall term, and completed his fellowship

48 Bethe, Hans Albrecht

travels with spring terms in Rome the follow-ing two years.

Bethe advanced his teaching career in1932, when he became a faculty member atthe highly regarded Tübingen University inGermany, founded in 1477 and modeled afterthe Renaissance methods of learning in Italy.But his assistant professorship came to a suddenend when Adolf Hitler (1889–1945) came intopower and summarily fired all of the Jews in ac-ademic positions. Bethe, who had a Jewishmother but did not consider himself Jewish,found out about his dismissal from a student whosaw it printed in the local newspaper. NeitherSommerfeld nor his student Bethe could find an-other position in Munich, so Bethe went backto England, this time to lecture at the Universityof Manchester for a year, then accepting a fel-lowship for the 1934 fall term at the Universityof Bristol. While he was at Bristol, CornellUniversity, located in Ithaca, New York, con-tacted Bethe and offered him a position that be-came the career move of a lifetime. Bethe packedhis bags and moved to the United States tobecome an assistant professor at Cornell. Thefollowing year, 1935, Bethe started the projectthat would earn him a permanent place in thehistory of astronomy.

About 20 years earlier, the British astro-physicist SIR ARTHUR STANLEY EDDINGTON

devoted a great deal of his efforts to uncoverthe internal structure of stars. At the time, thetheoretical physicist HENRY NORRIS RUSSELL

held the leading theory that a star’s energy wasgenerated through gravitational contraction.But Eddington thought it had something to dowith radiation pressure, espousing the theorythat the actual energy source was from a “trans-mutation of elements,” in other words, some sortof conversion of hydrogen into helium that re-sulted in an energy release. But no definitive an-swer was found.

Around 1930, the collaborating team ofAustrian physicist Fritz Houtermans (1903–66)

and British physicist Robert d’Escourt Atkinson(1893–1981) published a paper using the newlyaccepted theory of relativity and quantum me-chanics explaining that fusion occurs in a star’scenter. Along came Bethe. In 1938, at a summitin Washington, D.C., leading physicists and as-tronomers were introduced to Bethe’s work onnuclear reactions.

Stars with a mass the size of the Sun orsmaller generate heat up to 16 million kelvins,burning hydrogen via the process known as theproton-proton chain—the fusion of hydrogeninto helium. This happens in several steps. First,two hydrogen protons combine—one protonturns into a neutron and in the process releasesa positron (an electron with a positive charge),and a neutrino (which has no charge), creatinga hydrogen isotope called deuterium. The neu-trino escapes, and the positron collides with anelectron, creating gamma rays. Next, a third hy-drogen proton combines with the deuterium andproduces a lightweight isotope of helium—thehelium nucleus now contains two protons andone neutron, and more high-radiation gammarays are released. Finally, two helium nuclei com-bine to produce an ordinary nucleus of helium,and releases two protons—hydrogen. The endresult is that six hydrogens combined to formone helium and two hydrogens. The mass thatis lost becomes energy, which is proved by ALBERT

EINSTEIN’s equation E 5 mc2.For stars more massive than the Sun with

temperatures exceeding 16 million kelvins, an-other process occurs. In this case, carbon servesas a catalyst for burning hydrogen. The fusionbegins with a hydrogen and carbon nucleusforming nitrogen. After a much more compli-cated combination, the carbon is converted intonitrogen and oxygen, and in the end releases onehelium and one carbon nucleus. Since there isthe same amount of carbon in the end of theprocess as the beginning, the cycle stars again.This is known as the CNO (carbon-nitrogen-oxygen) cycle.

Bethe, Hans Albrecht 49

Bethe’s work on nuclear reactions from 1935through 1938 became his most famous work,and is considered one of the greatest accom-plishments in science in the 20th century, withfar-reaching effects for other scientists. FRITZ

ZWICKY ran experiments that confirmed Bethe’stheories. SUBRAHMANYAN CHANDRASEKHAR cre-ated the Chandra limit and opened the doors toexploring the collapse of stars, which was subse-quently picked up by Roger Penrose (1931– )and SIR STEPHEN WILLIAM HAWKING. RALPH

ASHER ALPHER, working under his doctoral ad-viser GEORGE GAMOW, created the Big Bang the-ory, determining when the universe was createdand the elements that were present in the be-ginning—hydrogen, helium, and lithium. FredHoyle (born 1915), WILLIAM ALFRED FOWLER,and Geoffrey and ELEANOR MARGARET PEACHEY

BURBIDGE showed how the nuclear fusion in starscould create the heavier elements, and how theyare dispersed throughout the galaxy throughsuch events as supernovae. In 1967 Bethe re-ceived the acknowledgment of a lifetime whenhe won the Nobel Prize in physics for his workon solar and stellar energy.

While Bethe was creating his amazing work,he was promoted to full professor of physics atCornell, and he settled in to continue on hispath of research and discovery. Then cameWorld War II.

Bethe was eager to contribute to the wareffort to help defeat Hitler. He left Cornell and traveled to the Massachusetts Institute ofTechnology (MIT), in Cambridge, Massachusetts,where he joined fellow scientists at the radiationlaboratory working on microwave radar. But insummer 1942 he was invited to take part in aproject that he initially wanted nothing to dowith because he felt it was entirely too implau-sible. Robert Oppenheimer (1904–67) was as-sembling the most brilliant scientific minds inthe United States to take part in the ManhattanProject—an effort to design and build the firstatomic bomb. Bethe’s participation was requested

and, after some consideration, he decided to jointhe team. Between 1943 and 1946 Bethe wasthe director of the theoretical physics divisionat the Los Alamos National Laboratory in LosAlamos, New Mexico. After the war, Bethe re-turned to Cornell and resumed his teaching andresearch.

In 1947 Bethe explained an occurrence ina hydrogen atom called the Lamb shift, whichhelped create the new field of quantum elec-trodynamics. He also did work involving theproduction via electromagnetic radiation ofparticles known as pi mesons—the lightest par-ticles consisting of a quark and an antiquark.The following year found Bethe as an unwill-ing participant in the science news event of thecentury—the announcement of the big bangtheory. Gamow, who wanted to create the playon words of “alpha, beta, gamma,” added Bethe’sname to Alpher’s paper on the big bang, sayingit was authored by Alpher, Bethe, and Gamow.Bethe refused to take credit for work that wasnot his own.

Bethe’s old friend and colleague EdwardTeller (1908–2003) from the Manhattan Project,contacted Bethe in 1949, hoping to persuadehim to return to Los Alamos and work on thenext big project—the hydrogen bomb. Bethedeclined on the basis that a war fought with ahydrogen bomb would result in humankind los-ing “the things we were fighting for.” He didconsult with the Los Alamos staff for about sixmonths in 1952, and has ever since been a vocalopponent to the H-bomb, working throughouthis life for disarmament.

In the mid-1950s Bethe began to look onceagain at the physics of atoms and collision the-ory, a subject he had worked on in the earlierdays of his career. He became the president ofthe President’s Science Advisory Committeefrom 1956 to 1959, working on the failed nego-tiations with the Soviet Union to ban nucleartesting. In 1995 the 88-year-old professor wasstill working for the good of the planet when he

50 Bode, Johann Elert

wrote an open letter calling on all of the scien-tists of the world to “cease and desist from workcreating, developing, improving, and manufac-turing further nuclear weapons . . .” adding that,as one of the few original Manhattan Project sci-entists still alive, he viewed with “horror thattens of thousands of such weapons have beenbuilt since that time, one hundred times morethan any of us at Los Alamos could ever haveimagined.”

In the 1990s Bethe worked on calculatingthe maximum mass of neutron stars, and in 1994he was the guest of honor at a Cornell physicssymposium entitled “Celebrating 60 Years atCornell with Hans Bethe,” where he was de-scribed as the “father of nuclear physics,” andthe “social conscience of physics.” Bethe’s careerhas continued into the 21st century. He wonthe prestigious Bruce Gold Medal from theAstronomical Society of the Pacific in 2001, andhe remains, at the age of 98, a professor atCornell University in New York. Between 1928and 1996 Bethe published 290 papers, and hecontinues to publish. He is the author of thebook The Road from Los Alamos (1991), and the1997 book Intermediate Quantum Mechanics,cowritten with R. W. Jackiw. With the excep-tion of his time at Los Alamos and a few sab-baticals to Columbia University, University ofCambridge, and Copenhagen, Bethe has neverleft his work at Cornell.

5 Bode, Johann Elert(1747–1826)GermanAstronomer

The self-taught German astronomer JohannBode is best known for the unusual mathemati-cal formula that bears his name and explains therelationship of planetary distances from the Sun.But his lifelong dedication to astronomy also in-cludes the discovery of five deep-sky objects, the

creation of several publications that were unlikeany ever done in the field, and 43 years of serv-ice at Berlin’s Academy of Science.

Bode’s scientific career began in 1768 when,at age 21, he published the first of many editionsto come of his textbook Anleitung zur Kenntnisdes gestirnten Himmels (Instruction for theknowledge of starry heavens). In 1772 Bode be-came an astronomer at Berlin’s Academy ofScience, where he stayed throughout his entirecareer.

Viewing the heavens and publishing aboutthem were the themes for Bode’s working life.In 1774 he teamed up with mathematician andpublisher Johann Lambert (1728–77), famousfor proving that pi is immeasurable, and perhapsmore important to Bode, the editor of an earlyastronomy-based almanac. The pair created oneof the first European publications dedicatedspecifically to scientific research, an ephemeris—a publication that lists data on the locations ofstars and other heavenly bodies for each day ofthe year. Originally named the AstronomischesJahrbuch oder Ephemeriden (Astronomical year-book and ephemeris), it was soon shortened tothe Astronomisches Jahrbuch, and finally to BerlinerAstronomisches Jahrbuch. It became an annualpublication that was widely used by astronomersand navigators as an accurate assessment of thenight skies.

With Bode’s publishing goals firmly estab-lished, he aimed his sights at the night skies andbegan searching for nebulae. In 1774 he madehis first two deep-sky discoveries, each of whichhe referred to as a “nebulas patch” in the UrsaMajor constellation: the Spiral Galaxy M81,which he described as “mostly round [with] adense nucleus in the middle,” and the IrregularGalaxy M82, also known as the Cigar Galaxy,which he considered to be “very pale” and “elon-gated” in shape. Both are at a distance of 12 mil-lion light-years (12,000 kly), and both werefound on December 31, 1774. Less than sixweeks later, on February 3, 1775, he discovered

Bode, Johann Elert 51

the Globular Cluster M53. At nearly 60 thou-sand light-years (60 kly), it appeared to Bode inthe “northern wing of Virgo,” looking “rathervivid and of round shape.” In 1776 Bode becamethe director of the Berlin Observatory.

Publishing gave Bode his next big careerboost, when he popularized a mathematical phe-nomenon that ultimately became known asBode’s Law. The origin of the formula came fromDavid Gregory (1659–1708), a University ofEdinburgh mathematics and astronomy profes-sor, who introduced the concept in his bookAstronomiae physicae et geometricae elementa (Theelements of astronomy). Printed first in Latin in1702, then in English in 1715, with a secondprinting in each language in 1726, Gregory’sbook suggested that the distances between theplanets and the Sun could be assigned a simplemathematical value: “supposing the distance ofthe Earth from the Sun to be divided into tenequal parts, of these the distance of Mercury willbe about four, of Venus seven, of Mars fifteen,of Jupiter fifty two, and that of Saturn ninetyfive[.]”

This is essentially the idea of the astro-nomical unit (AU), in which the distance fromthe Earth to the Sun is 1 AU, and the distancesof the remaining planets are expressed as aratio.

The idea resurfaced in 1724, when theGerman mathematician, philosopher, and pro-lific writer Christian Wolff (1679–1754) men-tioned the relationships in his book VernünfftigeGedanken von den Absichten der natürlichen Dinge.It faded into obscurity for another 40 years, butemerged again thanks to Swiss philosopherCharles Bonnet (1720–93), who became famousas the first to propose a scientific theory ofevolution. Bonnet wrote about the ratios in his1764 book, Contemplation de la Nature (Thecontemplation of nature), which was subse-quently translated into several languages.

In 1766 Johann Titius (1729–96), astronomer,mathematician, and professor at the University

of Wittenberg, Germany, became the Germantranslator of Bonnet’s popular book. But whenhe got to the text explaining the relationshipbetween the distances of the planets, Titiusadded his own formula to his translation. First,a set of numbers is created starting with 0, then3, then doubling each subsequent number, cre-ating the series of numbers 0, 3, 6, 12, 24, 48,96, 192, 384, and so on. The next step is to add4 to each number, creating the new series 4, 7,10, 16, 28, 52, 100, 196, 388, and so on. Thefinal step is to divide this new group of num-bers by 10, which results in .4, .7, 1.0, 1.6, 2.8,5.2, 10.0, 19.6, 38.8, etc. This last group of num-bers gives the location of the known planets bytheir distances from the Sun in AU. Titius failedto note that this was his own work, and it wasnot until his second translation of Bonnet’sbook was printed two years later, in 1768, thathe pointed this out in an added footnote, clear-ing things up. Not that it mattered. No one no-ticed the concept.

But that same year Bode’s Anleitung zurKenntniss des gestirnten Himmels was printed, andit became a well-received and widely read as-tronomy textbook—so much so that he revisedit and reprinted it in 1772, and in this editionhe added Titius’s formula. As with his predeces-sors, Bode included the information in his ownbook without mentioning the origin of the work.But unlike the earlier authors, Bode was a muchmore public figure and a highly regarded as-tronomer. So when the concept was publishedin his book, it was immediately accepted and be-came known as Bode’s Law.

Since Bode’s Law gave the nearly perfect lo-cations of the then-known planets, Mercury at.4 AU (actual distance is 0.39), Venus at .7 (ac-tual 0.72), Earth at 1.0, Mars at 1.6 (actual 1.52),Jupiter at 5.2, and Saturn at 10.0 (actual 9.54),speculation was high that there were more plan-ets waiting to be discovered. The search was on,with a sense of certainty that Bode’s Law wouldlead to new discoveries.

52 Bode, Johann Elert

The next several years proved fruitful forBode. His publishing goals were ambitious. In1777 he created a compilation of all of the knownnebulous stars and clusters and published it inAstronomisches Jahrbuch for the 1779 calendaryear. Using data recorded by Johannes Hevelius(1611–87), along with the catalog compiled in atwo-year journey to the Cape of Good Hope byFrench astronomer Nicolas-Louis de Lacaille(1713–62), and CHARLES MESSIER’s 1771 deep-sky catalog, Bode created the Complete Catalogueof Hitherto Observed Nebulous Stars and StarClusters, consisting of 75 entries, many of which,because of their creators’ mistakes, did not actu-ally exist. Not one to skimp on his own obser-vational tasks, Bode dutifully ended the year bydiscovering the Globular Cluster M92 at ap-proximately 26 kly, on December 27, 1777, inthe Hercules constellation.

The Complete Catalogue of Hitherto ObservedNebulous Stars and Star Clusters grew by two ob-jects in its 1779 printing. Bode added his dis-covery of M92, which he described as “. . . amostly round figure with a pale glimmer of light,”and his newest nebula, M64, which he found onApril 4, 1779.

But on March 23 the Welsh astronomerEdward Pigott (1753–1825) had also found thenebula, just 12 days before Bode’s discovery, al-though his discovery was not published until1781. Messier found it as well, on March 1, 1780,and published his finding in the summer of thatyear. For more than two centuries, most forgotthat Pigott had rightful title to the discovery, un-til April 2002, when it was uncovered by Britishastrophysicist Bryn Jones. Pigott and Bode arenow considered codiscoverers of the SpiralGalaxy M64.

Bode’s discovery of a comet in 1779—named C/1779 A1, 1779 Bode—led to a slew ofnew discoveries by other astronomers. Six newnebula were found, by astronomers AntoineDarquier de Pellepoix (1718–1802), who dis-covered the Ring Nebula M57 (2.3 kly), Johann

Gottfried Koehler, who discovered the EllipticalGalaxy M59 (60,000 kly) and the Spiral GalaxyM60 (60,000 kly), Barnabas Oriani (1752–1832),who discovered the Spiral Galaxy M61 (60,000kly) and Messier, who discovered the GlobularCluster M56 (nearly 33 kly) and the SpiralGalaxy M58 (60,000 kly). All were discoveredwhile observing Bode’s comet.

Finally, in 1781 the solar system’s seventhplanet was found in the constellation Gemini,by the amateur astronomer SIR WILLIAM

HERSCHEL, located at 19.18 AU, near the 19.6AU location predicted by Bode’s Law.

In honor of Herschel’s discovery, Bode cre-ated a new constellation that he namedHerschels Teleskop, depicting the instrumentHerschel used in his momentous discovery, andplaced next to the constellation Auriga.

As astronomers around the world observedthe new planet, Bode was more than happy tocollect and print their data. During his researchBode found evidence that it had actually beenseen at least twice before; first in 1690 by JohnFlamsteed (1646–1719), who designated it in hiscatalog as star 34 Tauri, and again in 1756 bythe German mathematician and astronomerTobias Mayer (1723–62).

In 1782 Bode turned his attention to a newpublishing format, creating a star atlas he namedDie Gestirne. It was the third in a succession ofatlases that began in 1792, when Flamsteedprinted his famous Atlas coelestis in response towhat he felt were problematic constellations inJOHANNES BAYER’s Uranometria. Next in linecame Atlas Céleste de Flamstéed, (Flamsteed’sCelestial Atlas), printed in 1776, by the Frenchastronomer Jean Fortin (ca. 1750–1831) in hom-age to Flamsteed’s atlas. Bode’s was the last touse Flamsteed’s data, although Bode did add anebulae he apparently discovered, named BodeI, which today is believed to possibly be the opencluster IC1434.

With the discovery of Herschel’s planet in1781, excitement about Bode’s Law was rekindled,

Bok, Bartholomeus Jan 53

and astronomers became even more convincedthat a planet had to exist in the gap betweenMars and Jupiter at 2.8 AU. A worldwide teamof astronomers cooperated to systematically di-vide the night sky and search for the missingplanet. In 1801 the Sicilian monk GIUSEPPE

PIAZZI, astronomer and director of the PalermoObservatory, found the next best thing to amissing planet—the minor planet or asteroidCeres, which he named Cerere di Ferdinandofor the goddess of grain and the patron goddessof Sicily and for King Ferdinand, Piazzi’s pa-tron. This was the first asteroid ever discov-ered, and remains the largest known, with a di-ameter of 623 miles, compared with thesmallest planet, Pluto, which has a diameter of1,457 miles, Earth, which is 7,926 miles, andthe largest planet, Jupiter, which rolls in at88,700 miles. At 2.77 AU, it was nearly ex-actly where Bode’s Law predicted a planetshould be.

Never far from publishing, Bode returnedagain to the monumental task of creating a newatlas, this time designing the biggest star atlasever made. Bode did not research the validityof any information, and he did not edit any-thing out, but rather made a compilation of allknown star atlases and catalogs. The book con-sists of 20 double-page plates, including all ofthe constellations that were ever suggested, withBode’s new constellations Apparatus Chemica,Custos Messium, Felis, Globus Aerostaticus,Honores Frederici, and Officina Typographica,none of which still exist, plus new figures forold constellations, more than 17,000 stars, andapproximately 2,000 nebulae discovered byHerschel. The constellations were representedby beautiful, stylistically new artwork, makingit unlike any atlas ever published. Bode’s Uran-ographia is considered the book that marked theend of an era in star atlases, giving way to mapsthat simply connected the stars with lines,rather than depicting the constellations withartistic figures.

Bode revised and reprinted Die Gestirne in1805, publishing it as Vorstellung der Gestirne(Introduction of the Luminaries). In addition tothe stars he added, Bode customarily revised theartwork of the constellations. This became knownas the Bode-Flamsteed atlas, and includes 34 mapsfeaturing 26 constellations that Bode could seefrom his observatory in Germany, plus plani-spheres, hemispheres, star clusters, and nebulas.

A long and full career at the Berlin Observatoryended after nearly 40 years when Bode retiredfrom his position as director in 1825. He con-tinued to publish Berliner Astronomisches Jahrbuchuntil his death in November of 1826, just oneyear after his retirement.

Bode’s Law was confirmed by the discoveryof Uranus in 1781 and the Ceres asteroid andsubsequent asteroid belt in 1801. But whenNeptune was discovered in 1846 at 30.06 AU,where no planet should have been, the idea fellfrom grace with the astronomical community.Not until Pluto’s discovery in 1930, at 39.44 AU,near the predicted 38.8 distance of Bode’s Law,did it come back into favor. To this date, thereremains no explanation of why Bode’s Law works.

The Spiral Galaxy M81, discovered in 1774by the 25-year-old Bode, is known as Bode’sGalaxy, and M82 and M81 are often referred to as Bode’s Nebulae or Bode’s Galaxies. Theasteroid first discovered on August 6, 1923, by Karl Wilhelm Reinmuth (1892–1979) inHeidelberg, Germany, was named AsteroidBodea, and in 1935, a crater on the Moon wasnamed in Bode’s honor.

5 Bok, Bartholomeus Jan (Bart Bok)(1906–1983)Dutch/AmericanAstronomer

In the 1930s and 1940s this Dutch astronomerconducted detailed investigations of the star-forming regions of the Milky Way Galaxy. He

54 Bok, Bartholomeus Jan

made careful studies of interstellar dust and gasand their relation with respect to star formation.In 1947 he discovered the small, near-spherical,dense dark nebulas, now called “Bok globules,”that contain enough interstellar material toeventually condense into star clusters.

Bartholomeus (Bart) Jan Bok was born onApril 28, 1906, in Hoorn, the Netherlands, toSergeant Major Jan Bok and Gesina Annetta vander Lee Bok. The family moved to The Hague in1918, where Bok attended high school. At age13 Bok knew he wanted to be an astronomer,having been strongly influenced in science byone of his schoolteachers. Throughout his high

school years he was an active amateur as-tronomer and became an admirer of HARLOW

SHAPLEY. Upon completing high school withhigh honors, he entered the University of Leidenin 1924 and remained there until 1927. Leidenproved to be a stimulating environment for thisyoung astronomer, where one of his classmateswas GERARD PETER KUIPER and among hisprofessors were ENJAR HERTZSPRUNG and JAN

HENDRIK OORT. His studies at the University ofLeiden provided Bok with a strong foundationin classical astronomy. In 1927 Bok went to theUniversity of Groningen to pursue his doctoraldegree.

In summer 1928 Bok attended the ThirdGeneral Assembly of the International Astro-nomical Union in Leiden, where two specialthings occurred that would greatly influence therest of his life. First, he met Harlow Shapley,who was then director of the Harvard CollegeObservatory. Shapley was impressed with theyoung Dutch astronomer and invited Bok tocome the following year to do his research on theMilky Way at the Harvard College Observatory.Second, Bok met and immediately fell in lovewith the American astronomer Priscilla Fairfield(1896–1975). Despite the fact she was 10 yearshis senior, Bok decided to marry Fairfield, whomhe called “the love of his life.” She eventuallyaccepted his proposal of matrimony and theywere wed in Troy, New York, on September 9,1929—just two days after Bok arrived in theUnited States to work at Harvard CollegeObservatory.

Bok’s marriage provided him with a founda-tion upon which he could build his career as aworld-class astronomer. As an astronomer her-self, Priscilla Fairfield Bok was an eager collab-orator on her husband’s astronomical projects.As a devoted wife, she was always there to pro-vide the gentle, introspective judgment neededto balance his often spontaneous and unre-strained approach to new opportunities andideas. Bok found the Harvard Observatory a

The Dutch-American astronomer Bart Bok at theUniversity of Arizona’s Steward Observatory in Tucson,a major astronomical facility under his directionbetween 1966 and 1970. Earlier in his career, hediscovered the small, cool (~10 kelvins) dark nebulasnow called “Bok globules” in his honor. (AIP EmilioSegrè Visual Archives, Physics Today Collection)

Boltzmann, Ludwig 55

most exciting place to do research. The couple’sfirst child, a son, was born in August 1930. Afterconducting research at the Harvard CollegeObservatory, Bok successfully defended his doc-toral dissertation, “A Study of the Eta CarinaeRegion,” at the University of Groningen on July6, 1932. He became an assistant professor atHarvard in 1933. Later that year, the couple’ssecond child, a daughter, arrived.

In the 1930s he performed detailed studiesof the Milky Way and published an importantmonograph, The Distribution of the Stars in Space,in 1937. The following year he became a natu-ralized citizen of the United States, and in 1939he earned a promotion to associate professor ofastronomy at Harvard College Observatory.Starting in about 1937, Bok collaborated withhis wife to write a book called The Milky Way.Five years later, the published book served as amuch-needed comprehensive treatment ofgalactic astronomy and became a very popularwork that went through five editions. As a re-sult, this collaborative writing effort attractedmany bright young minds to the field of astron-omy. In 1946 Harlow Shapley appointed Bok asthe associate director of the Harvard CollegeObservatory—a position he kept until Shapleyretired in 1952.

Bart Bok became a full professor of astron-omy at the Harvard College Observatory in1947. That same year he also made his most fa-mous astronomical discovery—the small, dark,cool (about 10 kelvins), almost circular, inter-stellar clouds observable against the backgroundof stars or luminous gas regions in the MilkyWay. Because they contain enough interstellarmaterial, these protostar regions, or “Bok glob-ules,” can be thought of as candidate stellarnurseries for some of the Galaxy’s lower-massstars.

Starting in the late 1940s Bok became in-volved in the process of establishing new obser-vatories in different parts of the world. Forexample, in February 1950 he and his family

traveled to South Africa and set up a new tele-scope at the Harvard Boyden Station. Bok es-pecially enjoyed this opportunity to view regionsof the Milky Way and the Magellanic Cloudsfrom Earth’s Southern Hemisphere.

Several years after Shapley retired as direc-tor of the Harvard College Observatory, Bok re-signed his professorship and departed the insti-tution he served for so many years. In January1957 he and his wife went to Australia, wherehe accepted a position as the director of theMount Stromlo Observatory, near Canberra. Healso became a professor of astronomy at theAustralian National University. Just before re-turning to the United States in 1966, Bok helpedestablish Australia’s Siding Spring Observatory.

When the couple returned to the UnitedStates, Bok become director of the University ofArizona’s Steward Observatory in Tucson andkept that position until he retired in 1970. Hesuffered a crushing blow when his wife died onNovember 19, 1975. He remained withdrawn forseveral years, emerging from his self-imposedsolitude in 1977 to receive the prestigious BruceMedal of the Astronomical Society of thePacific. He resumed some of his astronomical ac-tivities in the early 1980s, but died suddenly onAugust 5, 1983, while making plans to attendan upcoming astronomical conference.

5 Boltzmann, Ludwig(1844–1906)AustrianPhysicist

This brilliant, though troubled, Austrian physi-cist developed statistical mechanics and thekinetic theory of gases. His pioneering workaffected many areas of science, including ther-modynamics and astronomy. In the 1870sand 1880s Boltzmann collaborated with JOSEF

STEFAN in creating an important physical prin-ciple, now called the Stefan-Boltzmann Law,

56 Boltzmann, Ludwig

that relates the total radiant energy output (orluminosity) of a star to the fourth power of itsabsolute temperature.

Ludwig Boltzmann was born on February 20,1844, in Vienna, Austria. His father was a gov-ernment official involved in taxation. Hestudied at the University of Vienna, earning adoctoral degree in physics in 1866. His disserta-tion was supervised by Stefan and involved thekinetic theory of gases. Following graduation,Boltzmann joined his academic adviser as anassistant at the university.

Starting in 1869 he held a series of profes-sorships in mathematics or physics at a numberof European universities. Boltzmann’s physicalrestlessness mirrored the hidden torment of his

mercurial personality that would swing himsuddenly from intellectual contentment into adeep depression. His academic appointmentsincluded the University of Graz (1869–73; 1876–79); the University of Vienna (1873–76;1894–1900; 1902–06); the University of Munich(1889–93), and the University of Leipzig (1900–02). On the positive side, his movement frominstitution to institution brought him into con-tact with many great 19th-century scientists,including ROBERT WILHELM BUNSEN, RUDOLF

JULIUS EMMANUEL CLAUSIUS, and GUSTAF ROBERT

KIRCHHOFF. Boltzmann was a popular lecturerand entertained diverse academic interests thatencompassed physics, mathematics, chemistry,and philosophy.

As a physicist, he is best remembered for hisinvention of statistical mechanics and its pio-neering application in thermodynamics. His the-oretical work helped scientists connect the prop-erties and behavior of individual atoms andmolecules (viewed statistically on the micro-scopic level) to the bulk properties and physicalbehavior (such as temperature and pressure) thata substance displayed when examined on the fa-miliar macroscopic level used in classical ther-modynamics. One key to this development wasBoltzmann’s equipartition of energy principle. Itstated that the total energy of an atom or mol-ecule is equally distributed, on an average basis,over its various translational kinetic energymodes. Boltzmann postulated that each energymode had a corresponding degree of freedom. Hefurther theorized that the average translationalenergy of a particle in an ideal gas was propor-tional to the absolute temperature of the gas.This principle provided an important connec-tion between the microscopic behavior of an in-credibly large number of atoms or molecules andmacroscopic physical behavior (such as temper-ature) that physicists could easily measure. Theconstant of proportionality in this relationshipis now called Boltzmann’s constant, for whichthe symbol “k” is usually assigned.

In the 1870s and 1880s Ludwig Boltzmann, thebrilliant Austrian physicist, collaborated with hismentor, Josef Stefan, to create the Stefan-Boltzmannlaw—an important physical principle now used byastronomers and astrophysicists to relate the totalradiant energy output (or luminosity) of a star to thefourth power of its absolute temperature. (University ofVienna, courtesy of AIP Emilio Segrè Visual Archives)

Boltzmann, Ludwig 57

Boltzmann developed his kinetic theory ofgases independent of the work of the greatScottish physicist James Clerk Maxwell (1831–79). Their complementary activities resultedin the Maxwell-Boltzmann distribution—amathematical description of the most probablevelocity of a gas molecule or atom as a functionof the absolute temperature of the gas. Thegreater the absolute temperature of the gas, thegreater will be the average velocity (or kineticenergy) of individual atoms or molecules.Considering a container filled with oxygen (O2)gas at a temperature of 300 kelvins (K), for ex-ample, the Maxwell-Boltzmann distributionpredicts that the most probable velocity of anoxygen molecule in that container is 395 metersper second.

In the late 1870s and early 1880s Boltzmanncollaborated with Stefan in developing the veryimportant physical principle that describes theamount of thermal energy radiated per unit timeby a blackbody. In physics, a blackbody is de-fined as a perfect emitter and perfect absorber ofelectromagnetic radiation. All objects emit ther-mal radiation by virtue of their temperature. Thehotter the body, the more radiant energy it emits.By 1884 Boltzmann had finished his theoreticalwork in support of Stefan’s observations of thethermal radiation emitted by blackbody radia-tors at various temperatures. The result of theircollaboration was the famous Stefan-Boltzmannlaw of thermal radiation. A physical principle ofgreat importance to both physicists and as-tronomers, this law states that the luminosity ofa blackbody is proportional to the fourth powerof the body’s absolute temperature. The constantof proportionality for this relationship is calledthe Stefan-Boltzmann constant, and scientistsusually assign this constant the symbol “s”—alowercase sigma in the Greek alphabet. TheStefan-Boltzmann law tells scientists that if theabsolute temperature of a blackbody doubles, forexample, its luminosity will increase by a fac-tor of 16.

The Sun and other stars closely approxi-mate the thermal radiation behavior of black-bodies, so astronomers often use the Stefan-Boltzmann law to approximate the radiantenergy output (or luminosity) of a stellar object.A visible star’s apparent temperature is also re-lated to its color. The coolest red stars (calledstellar spectral class “M” stars), such as Betelgeuse,have a typical surface temperature of less than3,500 K. However, very large hot blue stars(called spectral class “B” stars), like Rigel, havesurface temperatures ranging from 11,000 to28,000 K.

In the mid-1890s Boltzmann related theclassical thermodynamic concept of entropy(symbol S), recently introduced by RudolfClausius (1822–88), to a probabilistic meas-urement of disorder. In its simplest form, S 5 kln V. Here, Boltzmann boldly defined entropy(S) as a natural logarithmic function of theprobability of a particular energy state (V). Thesymbol k again represents Boltzmann’s constant.This important equation is even engraved onhis tombstone.

Toward the end of his life, Boltzmann en-countered very strong academic and personalopposition to his atomistic views. Many eminentEuropean scientists of this period could not graspthe true significance of the statistical nature ofhis reasoning. One of his most bitter professionaland personal opponents was the Austrian physi-cist Ernest Mach (1838–1916), who as chair ofhistory and philosophy of science at theUniversity of Vienna essentially forced the bril-liant but depressed Boltzmann to leave that in-stitution and move to the University of Leipzigin 1900.

Boltzmann continued to defend his statisti-cal approach to thermodynamics and his beliefin the atomic structure of matter, but he couldnot handle having to continually defend histheories against mounting opposition in certainacademic circles. So, while on holiday with hiswife and daughter at the Bay of Duino, near

58 Bradley, James

Trieste, Austria (now part of Italy), Boltzmannhanged himself in his hotel room on October 5,1906, as his wife and child enjoyed a swim. Wasthe tragic suicide of this brilliant physicist theresult of a lack of professional acceptance of hiswork or the self-destructive climax of his life-long battle with bipolar disorder? No one cansay for sure. Sadly, at the time of his death, othergreat physicists were performing key experimentsthat would soon prove Boltzmann’s atomisticphilosophy and life’s work correct.

5 Bradley, James(1693–1762)BritishAstronomer

James Bradley was the 18th-century Englishminister turned astronomer who made two im-portant astronomical discoveries. His first wasthe aberration of starlight, announced in 1728.It represented the first observational proofthat Earth moves in space, confirming theCopernican hypothesis. His second discoverywas that of nutation—a small wobbling varia-tion in procession of Earth’s rotational axis,reported in 1748, after 19 years of careful obser-vation. Upon the death of the legendary SIR

EDMUND HALLEY in 1742, Bradley was appointedas the third Astronomer Royal of England.

He was born sometime in March 1693 (theprecise date is not recorded) in Sherborne,England. As a young child, Bradley was beingprepared for a life in the ministry when he suf-fered an attack of smallpox. His uncle, theReverend James Pound, introduced Bradley to as-tronomy while nursing him back to health. TheReverend Pound was an avid amateur astronomerand friend of Halley. Before long, Bradley beganto demonstrate his great observational skills ashe practiced amateur astronomy while studyingto become a vicar in the Church of England. By1718 Bradley’s talents sufficiently impressed

England’s second Astronomer Royal, and he en-couraged the young man to pursue astronomy asa career. Halley also recommended that Bradleybe elected as a fellow of the Royal Society inLondon.

As a result of this encouragement, Bradleyabandoned any thoughts of an ecclesiastical ca-reer. In 1721 he accepted an appointment to theSavilian Chair of Astronomy at the Universityof Oxford. Throughout his career as an as-tronomer, Bradley concentrated his efforts onmaking improvements in the precise observationof stellar positions. For example, in 1725 hestarted on his personal quest to be the first as-tronomer to measure stellar parallax—the verysmall apparent change in the position of a starwhen viewed by an observer on Earth as theplanet reaches opposing extremes of its ellipti-cal orbit around the Sun. However, the difficultmeasurement of stellar parallax managed to baf-fle and elude all astronomers, including Bradley,until FRIEDRICH WILHELM BESSEL accomplishedthe task in 1838. Nevertheless, while searchingfor stellar parallax, Bradley accidentally discov-ered another very important physical phenome-non that he called the aberration of starlight.

The aberration of starlight is the tiny ap-parent displacement of the position of a star fromits true position due to a combination of the fi-nite velocity of light and the motion of an ob-server across the path of the incident starlight.For example, an observer on Earth would haveEarth’s orbital velocity around the Sun, approx-imately 30 kilometers per second. As a result ofthis orbital motion effect, during the course of ayear the light from a “fixed” star appears to movein a small ellipse around its mean position onthe celestial sphere.

By a stroke of good fortune, on December 3,1725, Bradley began observing the star GammaDraconis, which was within the field of view ofhis large telescope pointed at zenith. He wasforced to look at the stars overhead because hisrefractor telescope was assembled in a long

Brahe, Tycho 59

chimney, with its telescopic lens above rooftopand its objective (viewing lens) below, in theunused fireplace. Bradley was actually attempt-ing to become the first astronomer to experi-mentally detect stellar parallax, and he used thisrelatively immobile telescope pointed at zenithto minimize atmospheric refraction. He viewedGamma Draconis again on December 17 and wasquite surprised to find that the position of thestar had shifted a tiny bit. But the apparent shiftwas not by the amount or in the direction ex-pected, if he was observing the phenomenon ofparallax. He continued these careful observa-tions over the course of an entire year and foundthat the position of Gamma Draconis actuallytraced out a very small ellipse.

Bradley puzzled over the Gamma Draconisproblem for about three years, but still could notsatisfactorily explain the cause of the displace-ment. Then, in 1728, while he was sailing onthe Thames River, inspiration suddenly struck ashe watched a small wind-direction flag on a mastchange directions. Curious, Bradley asked asailor whether the wind had changed directions.The sailor informed him that the direction ofwind had not changed. So Bradley realized thatthe changing position of the small flag was dueto the combined motion of the boat and of thewind. This connection helped him solve theGamma Draconis displacement mystery.

Based on the previous attempts by theDanish astronomer Olaus Roemer (1644–1710)to measure the velocity of light, Bradley hy-pothesized correctly that light must travel at avery rapid, finite velocity. He also further spec-ulated that a ray of starlight traveling from thetop of his tall telescope to the bottom wouldhave its image displaced in the objective everso slightly by Earth’s orbital motion. Bradley finally recognized that the mysterious annualshift of the apparent position of GammaDraconis, first in one direction and then in another, was due to the combined motion ofstarlight and Earth’s annual orbital motion

around the Sun. So it happened that early inhis career as an astronomer, Bradley made a major discovery—the aberration of starlight.This discovery was the first observational proofthat Earth moved in space, confirming theCopernican hypothesis.

Bradley soon constructed a new telescope,one not placed in a chimney, so he could makeprecise observations of other stars. Starting in1728 and continuing for many years, Bradley pre-cisely recorded many stellar positions. His effortsgreatly improved upon the earlier work of manynotable astronomers, including England’s firstAstronomer Royal, John Flamsteed (1646–1719).His ability to make precise measurements ledhim to a second important astronomical discov-ery. He found that Earth’s axis experienced smallperiodic shifts that he called “nutation” afterthe Latin word nutare, “to nod.” The new phe-nomenon, characterized as an irregular wob-bling superimposed upon the overall precessionof Earth’s rotational axis, is primarily caused bythe gravitational influence of the Moon, as ittravels along its somewhat irregular orbit aroundEarth. Bradley waited almost two decades, until1748, to publish this discovery, because he wantedto carefully study and confirm the very subtleshifts in stellar positions before announcing hisfindings.

When Halley died in 1742, Bradley wasappointed as England’s third Astronomer Royal.He most competently served in that distin-guished post until his death on July 13, 1762, inChalford, England.

5 Brahe, Tycho (Tÿge Brahe)(1546–1601)DanishAstronomer, Mathematician,Cartographer

History has recorded that if any of the great sci-entists had a nose for astronomy, it was Tycho

60 Brahe, Tycho

Brahe. Born December 14, 1546, to an aristo-cratic family in Knudstrup, Denmark, TÿgeBrage spent the better part of his 54 years be-coming both a master of science and a master-ful entrepreneur. (He adopted the Latin form ofTÿge, Tycho, when he was about 15.)

Brahe had the opportunity to study the sci-ences thanks in large part to his father’s wealthand power. Otte Brahe was a member ofDenmark’s elite ruling oligarchy, Rigsraad, andwas the first in an impressive line of patrons forthe studious young Brahe. On April 19, 1559, atage 12, Tycho began his lessons in earnest at theUniversity of Copenhagen. It was here, on August21, 1560, that he experienced a solar eclipse that,according to philosopher Pierre Gassendi, turnedBrahe’s interest toward astronomy.

After three years in Copenhagen, Brahe leftto attend the University of Leipzig, where for thenext three years he focused on humanities andastronomy. With his father’s funds available topay for travel and continued studies, Brahe ex-plored several universities over the followingtwo years, including Wittenberg, which he leftbecause of an outbreak of the plague, Rostock,and finally Basel.

It was while at Rostock that the hotheadedyoung Brahe took on fellow noble scholar,Manderup Parsbjerg, in a heated debate overwhich of the two was the better mathematician.This led to a duel with swords, and on December29, 1566, by the time their score was settled the20-year-old Tycho had forever lost the end ofhis nose.

Otte Brahe’s death in 1571 left Tycho a sub-stantial estate, consisting of assets including morethan 200 farms. Even after dividing the assets withhis brother, the 25-year-old Brahe had enoughfunds to live comfortably for the rest of his life.

Truly a scholar of science, Brahe’s breadth ofexpertise included astronomy, astrology, meteorol-ogy, iatrochemistry, cartography, instrumentation,pharmacology, and mathematics. His first majorastronomical discovery occurred in 1572, when hefound a new star in the constellation Cassiopeia,

which he named Stella Nova. In truth, this wasa supernova, one of three famous supernovaevents in the history of astronomy—one occur-ring in 1054; and another in 1604 observed byGALILEO GALILEI and JOHANNES KEPLER as anova, then finally determined to be a supernovasome 350 years later by WILHELM HEINRICH

WALTER BAADE.By mid-1573 Brahe met Kirsten Jörgensdatter,

a priest’s daughter, and the two married andeventually had a family of eight children. By1574 it was clear that Brahe was ready to makehimself, and his science, known to the world. Hepresented his first lecture, on mathematics, atthe University of Copenhagen. By 1577, at age30, he was offered what many would have con-sidered the enviable position of rector at theuniversity.

But six months earlier Brahe had received anotice from a new patron, King Frederick II, of-fering him an island, Hven, on which Tychocould build an observatory and leave his legacy.The castle Uranienborg was meant to be Brahe’sastronomical haven. All expenses would be pro-vided by the king to build, maintain, and pros-per, for the rest of Brahe’s life. The foundationwas started with a helping hand from the Frenchambassador, Charles Dançay, who placed thefirst stone in the castle’s wall.

Over the next few years, Tycho participatedin more than stargazing. He continued amassingassets and significant revenue in an effort to se-cure his status as nobility in his own right. Hewas granted farms, a fiefdom, and the positionof canon in Roskilde cathedral in 1579, whichhe held for nearly 20 years.

But in 1597 Brahe’s time at Hven came to anend, and on April 22, after losing royal supportfor his work, the astronomer left his haven of 21years, writing, “boring weather on a boring day.”After a trip to Wandsbech, near Hamburg, Brahesettled in Prague. The following year, Brahewrote Mechanica, in which he described many ofthe extraordinary instruments he had designedover the past 20 years. In an attempt to elicit

Braun, Wernher Magnus von 61

support for his work, Brahe dedicated the pieceto the Holy Roman Emperor Rudolf II. And itworked. The emperor spent an estimated 10,000guldens on a house for Brahe in Prague, and in1599 appointed him imperial mathematician.

It was during the following year that Brahe,who was a patron himself, employed Kepler.Brahe’s system of explaining the Earth and itsplace in the universe was flawed, but it gaveKepler an extraordinary opportunity that ulti-mately concluded in proving the correct natureof our solar system.

Ever concerned with his status, Brahe ap-plied for the rank of nobility in February 1601.Several months later, while having dinner withBaron Peter Vok Rosenberg in Prague, Brahe be-came quite ill. Over the next few days, his con-dition worsened with fever, and on October 24,1601, the noted scientist and mathematician ut-tered his last words to Kepler: “Don’t let meseem to have lived in vain.” On November 11,1601, Brahe was buried in Prague as nobility.

Kepler’s work ensured that Brahe got his fi-nal wish. While Kepler fundamentally sup-ported, and helped prove, the Copernican the-ory of a heliocentric universe, disproving Brahe’ssystem of the planets revolving around the Sunand all revolving around the Earth, it was Brahe’sextremely accurate observations of Mars that ledto Kepler’s conclusions and the creation of thelaws of planetary motion.

5 Braun, Wernher Magnus von(1912–1977)German/AmericanRocket Engineer

The brilliant rocket engineer Wernher von Braunturned the impossible dream of interplanetaryspace travel into a reality. He started by devel-oping the first modern ballistic missile, the liq-uid-fueled V-2 rocket, for the German army. Hethen assisted the United States by developing afamily of ballistic missiles for the U.S. Army

and later a family of powerful space launch ve-hicles for the National Aeronautics and SpaceAdministration (NASA). One of his giantSaturn V rockets successfully sent the first hu-man explorers to the Moon’s surface in July1969, as part of NASA’s Apollo Project.

Braun was born on March 23, 1912, inWirsitz, Germany (now Wyrzsk, Poland). He wasthe second of three sons of Baron Magnus vonBraun and Baroness Emmy von Quistorp. As a

The brilliant rocket engineer Wernher von Braun poseswith a Saturn IB launch vehicle perched on its pad atthe Kennedy Space Center in 1968. Von Braundevoted his professional life to creating ever morepowerful liquid-propellant rockets. In 1958 he quicklyadapted a U.S. Army rocket to carry the first U.S.satellite (Explorer 1) into orbit around Earth. Then inthe 1960s, he developed the family of powerful Saturnrockets for NASA. Starting in July 1969, his giantSaturn V rockets rumbled skyward, successfullysending teams of human explorers to the Moon’ssurface in timely fulfillment of President John F.Kennedy’s bold lunar exploration commitment.(Courtesy of NASA/Marshall Space Flight Center)

62 Braun, Wernher Magnus von

young man, he enjoyed the science fiction nov-els of Jules Verne and H. G. Wells, which kin-dled his lifelong interest in space exploration.HERMANN JULIUS OBERTH’s book The Rocket intoInterplanetary Space (1923) introduced him torockets. In 1929 Braun received additional inspi-ration from Oberth’s realistic “cinematic” rocketthat appeared in Fritz Lang’s (1890–1976) motionpicture Die Frau im Mond (The woman in themoon). That same year, he became a foundingmember of Verein für Raumschiffahrt, or VFR, theGerman Society for Space Travel. Through theVFR, he came into contact with Oberth andother German rocket enthusiasts. He also usedthe VFR to carry out liquid propellant rocket ex-periments near Berlin in the early 1930s.

He enrolled at the Berlin Institute of Tech-nology in 1930. Two years later, at age 20, hereceived his bachelor’s degree in mechanicalengineering. In 1932 he entered the Universityof Berlin, where as a graduate student he receiveda modest rocket research grant from a Germanarmy officer, Artillery Captain Walter Dorn-berger (1895–1980). This effort ended in disap-pointment when Braun’s new rocket failed tofunction before an audience of military officialsin 1932. But the young graduate so impressedDornberger that he hired him as a civilian engi-neer to lead the German army’s new rocketartillery unit. In 1934 Braun received his Ph.D.degree in physics from the University of Berlin.A portion of his doctoral research involved test-ing small liquid-propellant rockets.

By 1934 Braun and Dornberger had assem-bled a rocket development team totaling 80 en-gineers at Kummersdorf, a test facility locatedsome 100 kilometers south of Berlin. That year,the Kummersdorf team successfully launchedtwo new rockets, nicknamed Max and Moritzafter German fairy tale characters. Max was amodest liquid-fueled rocket, and Moritz flew toaltitudes of about two kilometers and carried agyroscopic guidance system. These successesearned the group additional research work from

the German military and a larger, more remotetest facility near the small coastal village ofPeenemünde, on the Baltic Sea.

The Kummersdorf team moved to Peenemündein April 1937. Soon after relocation, von Braun’steam began test firing the A-3 rocket, whichwas plagued with many problems. As WorldWar II approached, the German military directedBraun to develop long-range military rockets andhe accelerated design efforts for the much largerA-4. At the same time, an extensive redesign ofthe troublesome A-3 rocket resulted in the A-5rocket.

When World War II started in 1939 Braun’steam began launching the A-5. The results ofthese tests gave Braun the technical confidencehe needed to pursue final development of theA-4 rocket—the world’s first long-range, liquid-fueled military ballistic missile.

The A-4’s state-of-the-art liquid-propellantengine burned alcohol and liquid oxygen, andwas approximately 14 meters long and 1.66 me-ters in diameter. These dimensions were inten-tionally selected to produce the largest possiblemobile military rocket capable of passing throughthe railway tunnels in Europe. Built within thesedesign constraints, the A-4 rocket had an oper-ational range of up to 275 kilometers.

Braun’s first attempt to launch the A-4rocket at Peenemünde occurred in September1942 and ended in disaster. As its engine cameto life, the test vehicle slowly rose from thelaunch pad for about one second. Then the en-gine’s thrust suddenly tapered off, causing therocket to slip back to Earth. As its guidance finscrumpled, the doomed rocket toppled over anddestroyed itself in a spectacular explosion. Butsuccess finally occurred on October 3, 1942. Inits third flight test, the experimental A-4 vehi-cle roared off the launch pad and reached an al-titude of 85 kilometers while traveling a totaldistance of 190 kilometers downrange fromPeenemünde. The successful flight marks thebirth of the modern military ballistic missile.

Braun, Wernher Magnus von 63

Impressed, senior German military officialsimmediately ordered the still-imperfect A-4rocket into mass production. By 1943 the war wasgoing badly for Nazi Germany, so Adolf Hitlerdecided to use the A-4 military rocket as avengeance weapon against Allied populationcenters. He named this long-range rocket theVergeltungwaffe-Zwei (Vengeance Weapon Two),or V-2. In September 1944 the German armystarted launching V-2 rockets armed with high-explosive warheads (about one metric ton)against London and southern England. Anotherkey target was the Belgian city of Antwerp,which served as a major supply port for the ad-vancing Allied forces. More than 1,500 V-2 rock-ets hit England, killing about 2,500 people andcausing extensive property damage. Another1,600 V-2 rockets attacked Antwerp and othercontinental targets. Although modest in size andpayload capacity when compared to modern mil-itary rockets, Braun’s V-2 significantly advancedthe state of rocketry and was a formidable, un-stoppable weapon that struck without warning.Fortunately, the V-2 rocket arrived too late tochange the outcome of World War II in Europe.

In May 1945 Braun, along with some 500 ofhis colleagues, fled westward from Peenemündeto escape the rapidly approaching Russian forces.Bringing along numerous plans, test vehicles,and important documents, he surrendered toU.S. forces at Reutte, Germany. Over the nextfew months, U.S. intelligence teams, underOperation Paperclip, interrogated many Germanrocket personnel and sorted through boxes ofcaptured documents.

Selected German engineers and scientistsaccompanied Braun and resettled in the UnitedStates to continue their rocketry work. At theend of the war, American troops also capturedhundreds of intact V-2 rockets. After Germany’sdefeat, Braun and his colleagues arrived at FortBliss, Texas, to help the U.S. Army (underProject Hermes) reassemble and launch capturedGerman V-2 rockets from the White Sands

Proving Ground in southern New Mexico.During this period, Braun also married Maria vonQuistorp on March 1, 1947. Relocated Germanengineers and captured V-2 rockets provided acommon technical heritage for the major militarymissiles initially developed by both the UnitedStates and the Soviet Union during the cold war.

In 1950 the U.S. Army moved Braun and histeam to the Redstone Arsenal near Huntsville,Alabama. At the Redstone Arsenal, Braun su-pervised development of early ballistic missiles,such as the Redstone and the Jupiter, for the U.S.Army. These missiles descended directly from thetechnology of the V-2 rocket. As the cold wararms race heated up, the U.S. Army made Braunchief of its ballistic weapons program.

Starting in fall 1952, Braun also providedtechnical support for the production of a beau-tifully illustrated series of visionary space travelarticles that appeared in Collier magazine. Theseries caught the eye of the American enter-tainment genius Walt Disney (1901–66). By themid-1950s Braun became a nationally recog-nized space travel advocate through his frequentappearances on television. Along with WaltDisney, Braun served as a host for an inspiringthree-part television series on human spaceflight and space exploration. Thanks to Braun’sinfluence, when the Disneyland theme parkopened in southern California in 1955 (the yearBraun became a U.S. citizen), its “Tomorrowland”section featured a “Space Station X-1” exhibitand a simulated rocket ride to the Moon. A gi-ant, 25-meter tall, needle-nosed rocket ship(personally designed by Willy Ley [1906–69]and Braun) also greeted visitors to the Moonride. During the mid-1950s, the Disney–Braunrelationship introduced millions of Americansto the possibility of the Space Age, which wasactually less than two years away.

On October 4, 1957, the Space Age arrivedwhen the former Soviet Union launched Sputnik1, Earth’s first artificial satellite. Following thesuccessful Soviet launches of the Sputnik 1 and

64 Bruno, Giordano

Sputnik 2 satellites and the disastrous failure ofthe first American Vanguard satellite mission inlate 1957, Braun’s rocket team at Huntsville wasgiven less than 90 days to develop and launchthe first U.S. satellite. On January 31, 1958, amodified U.S. Army Jupiter C missile, called theJuno 1 launch vehicle, rumbled into orbit fromCape Canaveral Air Force Station. UnderBraun’s direction, this hastily converted militaryrocket successfully propelled Explorer 1 intoEarth orbit. The Explorer 1 satellite was a highlyaccelerated joint project of the Army BallisticMissile Agency (AMBA) and the Jet PropulsionLaboratory (JPL) in Pasadena, California. Thespacecraft carried an instrument package pro-vided by JAMES ALFRED VAN ALLEN, who dis-covered Earth’s trapped radiation belts.

In 1960 the U.S. government transferred ad-ministration of Braun’s rocket development cen-ter at Huntsville from the U.S. Army to a newlycreated civilian space agency called the NationalAeronautics and Space Administration (NASA).Within a year, President John F. Kennedy madea bold decision to put U.S. astronauts on theMoon within a decade. The president’s decisiongave Braun the high-level mandate he needed tobuild giant new rockets. On July 20, 1969, twoApollo astronauts, Neil Armstrong (born 1930)and Edwin (Buzz) Aldrin (born 1930), becamethe first human beings to walk on the Moon. Theyhad gotten to the lunar surface because of Braun’sflawlessly performing Saturn V launch vehicle.

As director of NASA’s Marshall Space FlightCenter in Huntsville, Alabama, Braun superviseddevelopment of the Saturn family of large, pow-erful rocket vehicles. The Saturn I, Saturn IB, andSaturn V vehicles were well-engineered expend-able rockets that successfully carried teams ofU.S. explorers to the Moon between 1968 and1972 and performed other important humanspace flight missions through 1975.

But just after the first human landings onthe Moon in 1969, NASA’s leadership decidedto move Braun from Huntsville and assigned

him to a Washington, D.C., headquarters “staffposition” in which he could “perform strategicplanning” for the agency. Braun, now an inter-nationally popular rocket scientist, had openlyexpressed desires to press on beyond the Moonmission and send human explorers to Mars. Thismade him a large political liability in a civilianspace agency that was now faced with shrink-ing budgets. In less than two years at NASAheadquarters, Braun decided to resign from thecivilian space agency. By 1972 the rapidly de-clining U.S. government interest in humanspace exploration clearly disappointed him. Hethen worked as a vice president of FairchildIndustries in Germantown, Maryland, until ill-ness forced him to retire on December 31, 1976.He died of a progressive cancer in Alexandria,Virginia, on June 16, 1977.

Braun’s aerospace engineering skills, leader-ship abilities, and technical vision formed aunique bridge between the dreams of thefounding fathers of astronautics: KONSTANTIN

EDVARDOVICH TSIOLKOVSKY, ROBERT HUTCHINGS

GODDARD, and Oberth and the first golden age of space exploration, which took place from approximately 1960 to 1989. In this unique period, human explorers walked on the Moonand robot spacecraft visited all the planets inthe solar system (except tiny Pluto) for the firsttime. Much of this was accomplished throughBraun’s rocket engineering genius, which helpedturn theory into powerful, well-engineeredrocket vehicles that shook the ground as theybroke the bonds of Earth on their journey toother worlds.

5 Bruno, Giordano (Filippo Bruno)(1548–1600)ItalianPhilosopher

While many would argue that Giordano Brunowas one of the great philosophical influences of

Bruno, Giordano 65

all time, it cannot be overlooked that his beliefsabout the universe and our place within it werein great part responsible for his execution at thehands of the Roman Inquisition.

In 1548, just five years after the death ofNICOLAS COPERNICUS, Filippo Bruno was born inNola, Italy, just outside Naples. Very little isknown about his early childhood. His father wasa soldier in Naples and the family was presum-ably poor, yet Bruno managed to begin his edu-cation in logic in Naples at about age 11. But itwas his studies in theology and philosophy, whichhe started at age 15, that began his life of piety,and eventually led to discord with the church.

From 1563 to 1576 Bruno was a member ofthe St. Dominico monastery in Naples. Whilethere, he changed his name to Giordano and be-gan studying both ancient and current philoso-phy. It was also during this time that he learnedof the works of Copernicus. Outspoken and per-haps dangerously frank, Bruno had the innateability to easily offend those around him. Thereis little doubt that he started exhibiting thesecharacteristics while in the monastery.

By the time he was 28, he had angered thechurch on more than one occasion. His first of-fense involved giving away images of saints.Charges were brought against him, most likelyas a disciplinary tactic to keep him in line (theywere dropped almost immediately), but in 1576they were brought back up in conjunction witha new charge of heresy for reading philosophi-cal texts that were out of favor with the church.Threatened with the possibility of proceedingsagainst him in Rome as a heretic, Bruno fled toavoid persecution, giving up all affiliation withthe Dominicans.

Over the next 16 years, Bruno led the lifeof a Renaissance man, wandering throughEurope, espousing his philosophy, and gainingfavor with royalty for his unique ways of think-ing. France’s King Henri III was so intrigued withBruno’s teachings in mnemonics that he helpedthe young philosopher obtain a university lec-

turing position. Bruno also began publishingbooks, in which he wove his philosophy throughdialogue and questioned the then-known reali-ties of the church, God, and the universe.

Of particular importance is his book The AshWednesday Supper (1584), which is typically citedas Bruno’s most significant perspective on as-tronomy. Following Copernicus’s lead, Bruno de-fied the church’s teachings, based purely onARISTOTLE, and supported the theory that theEarth is not the center of the universe. Bruno wenteven further to argue that the universe is infinite,and imagined that within this infinite universethere exists an infinite number of suns andearths. He believed that our Sun and Earth,when looked at from other vantage points,would look like any other stars. Using logic, Brunothreatened current knowledge. Unfortunately, thiswas tantamount to challenging the foundation ofthe church, thus defying God.

Bruno’s grace with the French aristocracyhelped him in his subsequent travels from 1583to 1592. His audience with royalty, includingQueen Elizabeth, and his nearly 20 books andplays contributed significantly to the acceptanceof debating his philosophical viewpoints in in-tellectual circles. In March 1592 he agreed toreturn to Venice by invitation of another aris-tocrat, Zuane Mocenigo, who proclaimed inter-est in learning about mnemonics.

Apparently, Mocenigo was hoping mnemon-ics would also involve black magic. WhenBruno was both unwilling and unable to deliverthe secrets of the occult, Mocenigo turned himover to the Venetian Inquisition for blasphemyand heresy, on May 23, 1592. The RomanInquisition took custody of Bruno the followingJanuary 27, and carried out its mandate to de-liver truth through interrogation and torture forthe next seven years. Unwilling to recant his be-liefs, Bruno was accused of heresy on January 20,1600, by the Holy Inquisition. All of his booksand writings were proclaimed “heretical anderroneous” and placed on the church’s Index of

66 Bunsen, Robert Wilhelm

Forbidden Books, and Bruno was sentenced todeath. Upon receiving his verdict, it is said thathe replied, “Perhaps your fear in passing judg-ment on me is greater than mine in receiving it.”

Giordano Bruno is known as a wanderer, anindependent thinker, a rationalist, and a mar-tyr. For the crime of freethinking, on February17, 1600, he was led from his dungeon in Rometo a stake in the Campo de’ Fiori square. Hismouth was bound with an iron gag made withspikes to pierce his tongue and palette, and hewas burned alive, becoming the first martyr ofmodern science.

5 Bunsen, Robert Wilhelm(1811–1899)GermanChemist, Spectroscopist

This innovative German chemist collaboratedwith GUSTAV ROBERT KIRCHHOFF in 1859 todevelop spectroscopy. Their innovative effortsentirely revolutionized astronomy by offering sci-entists a new and unique way to determine thechemical composition of distant celestial bodies.An accomplished experimentalist, Bunsen alsomade numerous contributions to the science ofchemistry, including improvement of the popu-lar laboratory gas burner that carries his name.

Robert Bunsen was born in Göttingen,Germany, on March 31, 1811, the youngest childin a family of four sons. The fact that his fatherwas an academician and served as a professor oflinguistics at the University of Göttingen al-lowed Bunsen to experience the academic envi-ronment at an early age and to select a similarprofessional path. He attended preparatoryschool in Holzminden and, upon graduation,enrolled at the University of Göttingen as achemistry major. An excellent student, Bunsengraduated in 1830 with his doctoral degree inchemistry at age 19. After graduation, the youngscholar traveled for an extensive period through-

out Germany and other countries in Europe, en-gaging in scientific discussions and visiting manylaboratories. He remained in Vienna from 1830to 1833. During these travels, Bunsen estab-lished a network of professional contacts thatwould prove very valuable during his long andillustrious career.

Upon his return to Germany, Bunsen ac-cepted a position as a lecturer in chemistry atthe University of Göttingen. It was here thathe also began an interesting set of experimentsinvestigating the insolubility of metal salts ofarsenious acid. As part of this pioneering chem-

The German chemist Robert Bunsen’s collaborationwith Gustav Kirchhoff in 1859 revolutionizedastronomy by allowing scientists to determine thechemical composition of distant luminous celestialbodies through spectroscopy. Despite his veryimportant role in the development of spectroscopy asa means of identifying individual chemical elements,most science students usually remember him as theperson who developed the popular gas burner thatbears his name. (AIP Emilio Segrè Visual Archives,E. Scott Barr Collection)

Bunsen, Robert Wilhelm 67

ical research at Göttingen, the young chemistdiscovered what is still the best antidote againstarsenic poisoning.

In 1836 Bunsen accepted a position at theUniversity of Kassel, but departed within twoyears to work at the University of Marsburg.While continuing his arsenic chemistry research,he experienced a near fatal laboratory explosionin 1836 that cost him an eye. After that acci-dent, his chemistry research still remained quitehazardous, because twice he nearly died from ar-senic poisoning. An intrepid and intelligent ex-perimenter, Bunsen was elected as a member ofthe Chemical Society of London in 1842.

He accepted a position at the University ofHeidelberg in 1852 and he remained with thisuniversity until he retired in 1889. Bunsen wasan outstanding teacher who never married andinstead focused all his time and energy on hislaboratory and his students. He eagerly taughtthe introductory chemistry courses normallyshunned by his academic colleagues. His lecturesemphasized experimentation and the value of in-dependent inquiry. A superb mentor, Bunsentaught many famous chemists, including theRussian Dmitri Mendeleev (1834–1907), whodeveloped the periodic table.

Bunsen’s continuing contributions to chem-istry were recognized by his induction to theAcadémie des Sciences in 1853 and by his elec-tion as a foreign fellow of the Royal Society ofLondon. Despite his numerous achievements inthe field of chemistry, he is often best remem-bered for his improvement of a simple labora-tory burner. Although the “Bunsen burner” wasactually invented by a technician, Peter Desaga,at the University of Heidelberg, Bunsen greatlyimproved the original device through his conceptof premixing the gas and air prior to combustionin order to provide a burner that yielded a high-temperature, nonluminous flame.

In 1859 Bunsen began his historic collab-oration with the German physicist GustavKirchhoff (1824–87)—a productive technical

association that changed the world of chemicalanalysis and astronomy. While JOSEPH vON

FRAUNHOFER’s earlier work laid the foundationsfor the science of spectroscopy, Bunsen andKirchhoff provided the key discovery that un-leashed the great power of spectroscopy. Theirclassic 1860 paper, “Chemical Analysis throughObservation of the Spectrum,” revealed the im-portant fact that each element has its own char-acteristic spectrum—much as fingerprints canhelp identify an individual human being. In alandmark experiment, they sent a beam of sun-light through a sodium flame. With the help oftheir primitive spectroscope (a prism, a cigarbox, and optical components scavenged fromtwo abandoned telescopes) they observed twodark lines on a brightly colored background justwhere the sodium D-lines of the Sun’s spectrumoccurred. Bunsen and Kirchhoff immediatelyconcluded that gases in the sodium flame wereabsorbing the D-line radiation from the Sun,creating an absorption spectrum. The sodiumD-line appears in emission as a bright, closelyspaced double yellow line, and in absorption asa dark double line against the yellow portion ofthe visible spectrum. The wavelengths of thesedouble bright emission lines and dark absorptionlines are identical and occur at 5889.96 angstromsand 5895.93 angstroms, respectively.

After some additional experimentation,they realized that the Fraunhofer lines were ac-tually absorption lines—that is, gases present inthe Sun’s outer atmosphere were absorbing someof the visible radiation coming from the solar in-terior. By comparing the solar lines with thespectra of known chemical elements, Bunsenand Kirchhoff detected a number of elementspresent in the Sun, the most abundant of whichwas hydrogen. Their pioneering discovery pavedthe way for other astronomers to examine theelemental composition of the Sun and otherstars and made spectroscopy one of modern as-tronomy’s most important tools. Just a few yearslater, in 1868, the British astronomer SIR JOSEPH

68 Burbidge, Eleanor Margaret Peachey

NORMAN LOCKYER attributed an unusual brightline that he detected in the solar spectrum to anentirely new element then unknown on Earth.He named the new element “helium,” afterhelios, the ancient Greek word for the Sun.

Bunsen and Kirchhoff then applied theirspectroscope to resolving elemental mysteriesright here on Earth. In 1861, for example, theydiscovered the fourth and fifth alkali metals,which they named cesium (from the Latincaesium, “sky blue”) and rubidium (from theLatin rubidus, “darkest red”). Today scientists usespectroscopy to identify individual chemical el-ements from the light each emits or absorbswhen heated to incandescence. Modern spectralanalyses trace their heritage directly back to thepioneering work of Bunsen and Kirchhoff.

The scientific community bestowed manyawards on Bunsen. In 1860 he received theRoyal Society’s Copley Medal; he shared the firstDavy Medal with Kirchhoff in 1877; and re-ceived the Albert Medal in 1898. After a life-time of technical accomplishment, Bunsen diedpeacefully in his sleep at his home in Heidelbergon August 16, 1899.

5 Burbidge, Eleanor Margaret Peachey(1919– )AmericanAstronomer, Astrophysicist

With a lot of science genes going for her,Margaret Burbidge was born Eleanor MargaretPeachey on August 12, 1919, in Davenport,Cheshire, England, to parents who both stud-ied chemistry at the Manchester School ofTechnology. She recalled in a biography that herinterest in astronomy was kindled during a boatcrossing from England to France when she wasfour years old and, having become seasick andconfined to her bunk, spent many hours gazingat the brilliant stars through her porthole.

After excelling in mathematics at privateprimary and secondary schools, Peachey was ex-cited to discover that the University of Londonoffered a degree in astronomy, unlike most col-leges at the time. She eventually earned her B.S.degree, the only woman in her class majoring inastronomy, and thanks to the frequent blackoutsduring German air raids was able to observethrough the observatory’s one functional tele-scope without the visual pollution of city lights.(A second telescope was rendered useless by abuzz bomb.)

She remained at the university’s observatoryafter the war, where she observed for several yearsuntil she received her Ph.D. in astronomy, even-tually becoming assistant director in the astron-omy department. While in that position sheapplied for a Carnegie Fellowship at the MountWilson Observatory, in the San Gabriel Moun-tains above Pasadena, California; she receivedher first taste of gender discrimination when toldin their response letter that women were notaccepted. The excuse was that the observatoryhad only one toilet!

Two lifetime milestones in one year do notoccur very often, but after receiving her Ph.D.in 1948, she also married her lifetime partnerand co-researcher Geoffrey Burbidge, a theo-retical physicist and her former physicsteacher.

Burbidge’s first significant appointment inthe United States was as a research fellow at theUniversity of Chicago’s Yerkes Observatory,where she worked from 1951 to 1953. Geoffreyalso did research at the university and, indeed,throughout Burbidge’s career her husband wouldaccompany her in associated academic positions.She then returned to England to do research atthe Cavendish Laboratory, which is in theDepartment of Physics at Cambridge University.It was here that the couple met the renownedBritish astronomer Sir Fred Hoyle (born 1915)and the American nuclear physicist WILLIAM

ALFRED FOWLER.

Burbidge, Eleanor Margaret Peachey 69

Burbidge returned to the United States in1955 when her husband was awarded theCarnegie Fellowship for astronomical research atthe Mount Wilson Observatory, the position forwhich Burbidge had previously been turneddown ostensibly because of the solitary toilet.When she won a fellowship from CaliforniaInstitute of Technology (Caltech), which alsowas affiliated with the then-famous Mount

Wilson telescope, she soon discovered that shenot only was barred from the dormitory at theobservatory, but also that women were notallowed to use any of the telescopes. However,she convinced administrators that she wasGeoffrey’s “assistant.” The pair, along with othercoworkers, protested the discrimination, but itwould be 10 years before the “no women” policywas overturned.

The English astrophysicist Eleanor Margaret Burbidge reviews images of quasars and various spiral galaxies in1980. Collaborating with her husband and other physicists in 1957, she published an important scientific paperthat described how nucleosynthesis creates elements of higher mass in the interior of stars. She also coauthored afundamental book on quasars in 1967 and became the first female director of the Royal Greenwich Observatory,serving in that post from 1972 to 1973. (AIP Emilio Segrè Visual Archives, Physics Today Collection)

70 Burbidge, Eleanor Margaret Peachey

In 1957 Burbidge returned to Chicago whenGeoffrey received a position as assistant profes-sor of astronomy at the Yerkes Observatory inWisconsin. To avoid charges of nepotism, whichshe stated “are always used against the wife,” shehad to settle for a position as an associate pro-fessor of astronomy at the university.

It was during this tenure that she coformu-lated what is known as the “B2FH Theory,”named for the principal authors: she, her hus-band, Fowler, and Hoyle. Based on the conceptthat there is no simple way by which the ele-ments could have formed, since space matter issubjected to different conditions, the theory pre-sented the then-revolutionary explanation thatthe elements were formed by nuclear reactionsinside stars. In 1959 the American AstronomicalSociety awarded the Burbidge husband-and-wifeteam the Helen B. Warner Prize for Astronomy,recognizing the importance of their theory to thenew field of nuclear astrophysics.

Yet another nepotism issue arose in 1962,when Geoffrey was given a position as professorin the Department of Physics at the Universityof California at San Diego (UCSD). SinceUCSD did not have a separate astronomy de-partment at the time, and the husband and wifewere prohibited from working together, Burbidgehad to accept a position in the chemistry de-partment. Two years later, the university abol-ished its nepotism rule and she joined Geoffreyas a full professor of physics.

During these years Burbidge had been pio-neering investigations into the nature of quasars,or quasi-stellar radio sources, which, in simpleterms, are galaxies billions of light-years awaythat can be detected only with radio telescopes.In 1967 she and Geoffrey published the bookQuasi-Stellar Objects, which even today remains aclassic in the field of quasar research and radioas-tronomy. She also delved into the nature ofgalaxies and, using the telescope at the MacDonaldObservatory operated by the University of Texasat Austin, she pioneered work in measuring the

spectra of more than 50 spiral galaxies, deter-mining their rotations, masses, and chemicalcompositions.

Burbidge took a leave from UCSD and re-turned to England in 1972 to take the positionas director of the Royal Greenwich Observatory,the oldest scientific institution in Great Britain.However, Geoffrey could not find a similar po-sition, so he stayed at UCSD. After a year hadpassed, she both missed her husband and grewfrustrated with bureaucratic stumbling blocks.She resigned her position and returned toUCSD, where she eventually became the direc-tor of the university’s Center for Astrophysicsand Space Sciences. In what must have been anemotionally satisfying event after so many yearsof gender discrimination and nepotism rules, in1976 she was named the first female presidentof the American Astronomical Society. One ofher first accomplishments was to get the organ-ization to refuse to hold meetings in states thathad not ratified the Equal Rights Amendment.Soon after that, in 1978, she was elected to theNational Academy of Sciences.

For years an idea had been rolling aroundthe back of Burbidge’s mind: Why not try to sta-tion a large telescope in space? When the con-cept of the Hubble Space Telescope was put forthby NASA, Burbidge helped design the faint ob-ject spectrograph (FOS), a high-resolution in-strument aboard the Hubble Space Telescope thatrecords the spectra of galaxies. Beginning in1990, she was the coprincipal investigator ofdata emanating from the FOS for the next sixyears.

One of the great pioneers in the field ofastronomy in the 20th century, Burbidge at age82 was still professor emeritus of astronomyand research professor at UCSD. She has wondozens of professional honors, prizes, and hon-orary degrees, and is noted as having turneddown the Annie J. Cannon Award in Astronomyfrom the American Association of UniversityWomen, a prestigious prize offered only to

Burbidge, Eleanor Margaret Peachey 71

women astronomers, on the ground that specialhonors and discrimination for women should beabolished.

In 1982 she became the first woman in the84-year history of the Astronomy Society of thePacific to win the Catherine Wolfe Bruce Medal,one of the highest honors in the field of astron-

omy, for “a lifetime of distinguished service andachievement.” In 1985 President Reagan pre-sented her with the National Medal of Science,and in 1988 she won the Albert Einstein WorldAward of Science Medal. The minor planet 5490has been named Burbidge in her honor.

72

C5 Campbell, William Wallace

(1862–1938)AmericanAstronomer

Early in the 20th century, the American as-tronomer William Campbell made pioneeringspectroscopic measurements of stellar motionsthat helped astronomers better understand themotion of our solar system within the Milky WayGalaxy and the overall phenomenon of galacticrotation. He perfected the technique of photo-graphically measuring radial velocities of stars,and discovered numerous spectroscopic binaries.Campbell also provided a more accurate confir-mation of ALBERT EINSTEIN’s theory of generalrelativity when he carefully measured the subtledeflection of a beam of starlight during his solareclipse expedition to Australia in 1922.

Campbell was born on April 11, 1862, inHancock County, Ohio. He experienced a child-hood of poverty and hardship on his family’sfarm. He originally enrolled in the civil engi-neering program at the University of Michigan.However, his encounter with SIMON NEWCOMB’swork Popular Astronomy (1878) convinced himto become an astronomer. After graduating fromthe University of Michigan in 1886, he accepteda position in the mathematics department at theUniversity of Colorado. After working for two

years in Colorado, Campbell returned to theUniversity of Michigan in 1888 and taught as-tronomy there until 1891. While teaching inColorado, he also met the student who becamehis wife. Betsey (Bess) Campbell proved to be avery important humanizing influence on herhusband, who was known for being domineeringand inflexible, personal traits that made him ex-tremely difficult to work with or for.

In 1890 he traveled west from Michigan tobecome a summer volunteer at the Lick Obser-vatory of the University of California, locatedon Mount Hamilton near San Jose. His hardwork and observing skills earned him a perma-nent position as astronomer on the staff of theobservatory the following year. On January 1,1901, he became director of the Lick Observa-tory and ruled that facility in such an autocraticmanner that his subordinates often privatelycalled him the czar of Mount Hamilton. In 1923he accepted an appointment as the president ofthe University of California (in Berkeley), buthe also retained his former position as the direc-tor of the Lick Observatory.

Wallace Campbell’s permanent move fromthe University of Michigan to California in 1891proved to be a major turning point in his careeras an astronomer. Until then, he had devotedhis observational efforts to the motion of comets.At the Lick Observatory, he brought about a

Campbell, William Wallace 73

American astronomer William Wallace Campbell in 1893, standing beside the 36-inch refractor telescope with itsspecially designed spectrograph at the Lick Observatory, on Mount Hamilton near San Jose, California. Campbellused this equipment to make pioneering measurements of the radial (line of sight) velocities of stars by measuringthe Doppler shift of their spectral lines. (AIP Emilio Segrè Visual Archives)

74 Cannon, Annie Jump

revolution in astronomical spectroscopy whenhe attached a specially designed spectrograph tothe Lick Observatory’s 36-inch refractor tele-scope—then the world’s largest. He used thispowerful instrument to measure stellar radial(that is, line of sight) velocities, by carefully ex-amining the telltale Doppler shifts of stellarspectral lines. He noted that when a star’sspectrum was “blueshifted,” it was approachingEarth; when “redshifted,” it was receding. Heperfected his spectroscopic techniques and in1913 published Stellar Motions, his classic text-book on the subject. In that same year, Campbellalso prepared a major catalog, listing the radialvelocities of more than 900 stars. He later ex-panded the catalog in 1928 to include 3,000stars. His precise work greatly improved knowl-edge of the Sun’s motion in the Milky Way andthe rotation of the Galaxy.

Campbell also used his spectroscopic skillsto show that the Martian atmosphere containedvery little water vapor—a finding that put himin direct conflict with other well-known as-tronomers at the end of the 19th century. Usingthe huge telescope and clear-sky advantages ofthe Lick Observatory, Campbell, who was neverdiplomatic, quickly disputed the plentiful watervapor position of SIR WILLIAM HUGGINS, SIR

JOSEPH NORMAN LOCKYER, and other famousEuropean astronomers. While Campbell was in-deed correct, the abrupt and argumentative wayhe presented his data won him few personalfriends within the international astronomicalcommunity.

He enjoyed participating in internationalsolar eclipse expeditions. His wife joined him onthese trips, and she was often put in charge ofthe expeditions provisions. During a 1922 solareclipse expedition in Australia, Campbell meas-ured the subtle deflection of a beam of starlightjust as it grazed the Sun’s surface. His precisemeasurements helped confirm Albert Einstein’stheory of general relativity and reinforced theprevious, but less precise, measurements made by

SIR ARTHUR STANLEY EDDINGTON during the1919 solar eclipse.

Campbell retired as the president of theUniversity of California (Berkeley) and as thedirector of the Lick Observatory in 1930. He andhis wife then moved to Washington, D.C., wherehe served as the president of the NationalAcademy of Sciences from 1931 to 1935.Returning to California, he spent the last threeyears of his life in San Francisco. On June 14,1938, he died by his own hand—driven to sui-cide by declining health and approaching totalblindness. William Campbell’s contributions toastronomy were acknowledged through severalprestigious awards. The French Academy pre-sented him with its Lalande Medal in 1903 andits Janssen Medal in 1910, the British RoyalAstronomical Society awarded him its GoldMedal in 1906, and the National Academy ofSciences of the United States gave him theHenry Draper Medal in 1906. Finally, in 1915,the Astronomical Society of the Pacific awardedCampbell its Bruce Gold Medal.

5 Cannon, Annie Jump(1863–1941)AmericanAstronomer

At the turn of the 20th century, the director ofthe Harvard College Observatory hired severalwomen as data analysts, not paying them verymuch but nevertheless remunerating them forreducing and filing complex data accumulatedfrom stellar observations. Many of these womenbecame respected members of the astronomicalcommunity. The most famous among them wasAnnie Jump Cannon, who became the mostprolific and studious star spectrum classifier inhistory, and eventually the world’s foremostauthority on classifying stars.

Born in Dover, Delaware, Cannon was only16 years old when she became one of the first

Cannon, Annie Jump 75

women from that state to be admitted to college.Her father was Wilson Cannon, a shipbuilderand state senator, and her mother, Wilson’s sec-ond wife, Mary Jump, taught her the constella-tions from the family’s “star book.” As a child,Cannon was fascinated by how crystal pendantson the candelabra separated sunlight into col-orful rainbow patterns. These two interests ledher to study physics and astronomy at Wellesley

College, where she learned how to make spec-troscopic measurements. After graduating in1884, and taking up the newly developed scienceof photography as an avocation, she traveledextensively with her camera.

During her travels she contracted scarletfever and was struck deaf, having to use a hear-ing aid for the rest of her life. However, this af-fliction is said to have honed her great powersof concentration, responsible for propelling herinto the highest ranks of astronomers of hertime.

After the death of her mother in 1894,Cannon returned to Wellesley to teach physics,and did further studies in astronomy at Radcliffe.In 1896 she became one of “Pickering’s women,”taking part in some of the first X-ray experi-ments, and on May 14 she made her first ob-servation of a star’s spectrum. At the time, theaccumulation of the massive stellar data wasfunded by Anna Draper, widow of the wealthyphysician and amateur astronomer HENRY

DRAPER. Pickering set up the Henry DraperMemorial as a long-term project to gather theoptical spectra of as many stars as possible.This had begun in 1886 and was carried on byseveral women, each using her own system ofclassification.

Eventually the work fell to Cannon, whothrew herself into the project with an intensityand devotion unparalleled in the history of as-tronomy. The speed with which she worked wasalmost superhuman. It is said that Cannon clas-sified 5,000 stars a month between 1911 and1915, and one report has it that before she wasthrough she had classified the spectra of morethan 400,000 stars.

She began by developing a classification sys-tem that utilized the best parts of those systemsdeveloped before her, and assigned a division ofstars into O, B, A, F, G, K, M categories, lead-ing to the famous “Oh, Be a Fine Girl, Kiss Me”mnemonic memorized by every astronomy studentsince. The classification catalog she ultimately

American astronomers Annie Jump Cannon (left) andHenrietta Swan Leavitt (right) outside the mainentrance to the Harvard College Observatory, wherethey worked under the supervision of Edward CharlesPickering to publish the Henry Draper Catalogue—anine-volume document that contained the spectralclassifications of more than 225,000 stars. Cannonwas the driving force behind the development of arefined system for classifying stellar spectra thatbecame known as the Harvard Classification System. (Courtesy AIP Emilio Segrè Visual Archives, ShapleyCollection)

76 Cassini, Giovanni Domenico

developed, called the HD Catalog, is still in usetoday as the cornerstone of modern spectro-scopic astronomy. She also published severalcatalogs of variable stars, 300 of which she dis-covered herself.

Cannon went on to win practically everyaward and honor the scientific community couldbestow. In 1911 she became curator of the ob-servatory; in 1923 she was reportedly declared tobe one of the “12 greatest living Americanwomen.” In 1925 she was the first woman toreceive an honorary doctorate degree fromOxford University, and in 1931 she received thecoveted Draper Gold Medal from the NationalAcademy of Sciences, again the first woman sohonored. The American Association of UniversityWomen named its annual award to the foremostwoman of science the Annie J. Cannon Award.In all, she received a total of six honorary doctoraldegrees.

Annie Jump Cannon died on April 13,1941, after 42 years of dedication at Harvard.She is one of only 20 women who have a lunarcrater named in her honor.

5 Cassini, Giovanni Domenico(Gian Domenico Cassini, Jean-Dominique Cassini, Cassini I)(1625–1712)Italian (naturalized French)Astronomer, Mathematician

Born in what is now Italy, but eventually be-coming a naturalized French citizen, Cassini isknown as the “Father of French Astronomy.” Hewas born on June 8, 1625, to Julia Crovesi andJacopo Cassini in the city of Perinaldo, whichwas either in the French county of Nice or theRepublic of Genoa, depending on the source,and is now a part of Italy. One of the great as-tronomers of his time, Cassini was also an ex-pert in hydraulics and engineering, specializingin river management and flood control.

Cassini reportedly studied for two years atVallebone before becoming a student, first at theJesuit college in Genoa and then at the abbeyof San Fructuoso, where he became very inter-ested in astrology. But after casually perusing abook on astronomy, which by this time was aseparate discipline, he decided to drop astrol-ogy and focus on learning astronomy instead.However, his technical background served himwell when he was consulted about the flood-ing of the river Po, and he worked for PopeAlexander VII to negotiate arrangements for thenavigation of the rivers Po and Remo. Later hewas named superintendent of the fortificationsof Fort Urban and the fortress of Perugia, andwas appointed to solve problems surrounding thecourse of the river Chiana, as well as supervis-ing effluent control of the rivers Tiber and Arno,which was causing friction between the pope andthe grand duke of Tuscany.

The extensive knowledge he had of bothastronomy and astrology, with the necessarymathematical ability to work in both fields,gave Cassini the foundation he needed for anew position offered to him in 1644, whenhe was invited by a powerful political figure inBologna, the marquis Cornelio Malvasia, tocome to the university and work in the newobservatory. It was an opportunity Cassinicould not, and did not, pass up, and it was thebeginning of a 20-year relationship with theuniversity.

By 1648 the new Panzano Observatory wasfinally built, and Cassini was able to start his ob-servations, which were initially aimed at theSun. Within two years he was also a professor ofastronomy and mathematics. By 1653 he was oc-cupied with a task that seemed nearly impossi-ble to carry out—he wanted to build a gnomonsimilar to the one he had seen at a church inSan Petrino, which had been built between themid-15th and early 16th centuries. The gnomonwould be used to calculate the altitude of theSun as the Sun cast a shadow over the sundial-

Cassini, Giovanni Domenico 77

like apparatus, but the one in San Petrino hadbeen obstructed and was worthless, and Cassiniwanted to build a much bigger device.

Cassini designed the new instrument andoversaw its completion. His calculations had tobe precise for it to work, and when it was finallyinstalled, it was perfect. This accomplishmentgave Cassini instant success and, more impor-tant, allowed him to start making observationswith this new tool. He published his work in abook entitled Specimen observationum bononien-sium in 1656 and dedicated it to the exiledQueen Christina of Sweden.

The period between 1656 and 1659 madeCassini’s name in the world of astronomicalscience. In these few years he calculated a newvalue of the inclination of the ecliptic as2308299150, the most precise of his era; he drewup a table of the atmospheric refractions, whichwere the most accurate for a century after hisdeath; and he proved that the orbital velocity ofthe Earth was not constant.

In 1661, even while doing his hydraulicwork on the flooding rivers, he worked out a wayto determine longitudes by observing solareclipses, but the Inquisitor of Modena refused toallow publication of his paper. It would be pub-lished 10 years later in France.

Cassini obtained one of the first long fo-cal lenses made by the lensmaker GiuseppeCampani, and began to study the planets. Withthese lenses he observed the shadows of Jupiter’smoons on the surface of the planet and calcu-lated their rotational period, and he observedJupiter’s Great Red Spot, which in turn allowedhim to calculate Jupiter’s rotational period. Atthis time he also evaluated Mars’s rotationalperiod.

All of this innovational astronomy gaveCassini a reputation that went beyond theboundaries of Italy. In France Louis XIV was de-ciding that France should become as prominentin the arts and sciences as it was in warfare andweaponry, and charged one of his ministers,

Colbert, with inviting Cassini to come to Franceand join France’s Académie Royale des Sciences,giving him an opportunity to work at the newobservatory then being built. However, this re-quired the permission of Cassini’s new boss, PopeClement IX, who generously gave his approval.If Italy wanted to keep Cassini for itself, thisproved a costly mistake, for when Cassini left,he only returned to Italy to visit relatives ormake observations.

Cassini reached Paris in 1669, and went tolive at the new observatory, where he was pro-vided with a sizable salary, a travel allowance,and free accommodations. In 1673 he requestedFrench nationality, changed his name from theItalian Giovanni Domenico to the French Jean-Dominique, married Genevieve de Laistre,daughter of a high-ranking military officer, andmoved into the castle of Thury, near Beauvais,as a family residence—which, coincidentally, wascrossed by the Paris meridian.

At the new observatory, Cassini started a se-ries of observations of the lunar surface, whichresulted in his writing a lunar atlas, a large map,and to propose a theory of the oscillation of theMoon. He also used his tables of refractions tocalculate the Mars parallax and that of the Sun.This information greatly increased the scale ofthe solar system at the time.

Of all the objects in the heavens, it is theplanet Saturn that is most closely associated withCassini’s name. While SIR WILLIAM HUYGENS

had discovered Titan, Saturn’s first satellite in1655, Cassini, working at the Paris Observatory,discovered four others: Iapetus in 1671, Rhea in1672, and Dione and Thetys in 1684. In 1675Cassini discovered that Saturn’s famous ring wasactually two rings separated by a dark space, nowcalled Cassini’s Division. He also recorded theflatness of the ring, and observed a cloudy stripparallel to Saturn’s equator. Eventually hesuggested that the ring was not solid, but com-posed of tiny “satellites” that could not be re-solved with currently available lenses, a thesis

78 Cavendish, Henry

borne out only recently by today’s observationaltechnology.

Cassini also made important measurementsof the Earth, and undertook an important geo-graphical work. He extended the meridian lineestablished from Paris to Amiens by Jean Picard(1620–82) and made great determinations oflongitudes. As young Jesuit priests studied underhim at the Paris Observatory and then went ontheir missionary assignments, Cassini began toreceive results of their observations from China,Africa, and America. He marked these on a largeplanisphere, 7.8 meters in diameter, and made apen-and-ink sketch on the ground at the obser-vatory. In this manner, the longitudes of distantcountries could be corrected more accuratelythan ever before.

Cassini carried on his research until 1711,when the strain of a lifetime of squintingthrough lenses, often at the Sun, rendered himtotally blind. He was always described as aman of kind and gentle demeanor, with apleasant nature and deeply religious, which al-lowed him to bear his blindness with goodcheer and stoicism. He died in the ParisObservatory on September 14, 1712. A space-craft launched in 1997 was sent on a seven-year voyage that successfully reached the Saturnsystem in July 2004, where it would gather dataand pictures never before available to as-tronomers. It is named Mission Cassini.

5 Cavendish, Henry(1731–1810)BritishChemist, Physicist

The reclusive Henry Cavendish was perhaps oneof the oddest, and yet one of the most impor-tant, scientists of the 18th century. He wasknown as an expert at scientific experimenta-tion, and dedicated his life completely to the study of science, resulting in the discovery

of hydrogen, determining the composition of air,and calculating the mean density of the Earth.But he was considered as eccentric as he was bril-liant, and led a life in which he almost neverspoke, not even to his household staff.

Cavendish was born to English nobility onOctober 10, 1731, in Nice, France, where hisfamily lived temporarily because of his mother’shealth. He was the oldest son of Lord CharlesCavendish and Lady Anne Gray. The duke ofDevonshire was his paternal grandfather andthe duke of Kent was his maternal grandfather.While little is known about his early education,it is safe to say that his family’s status andwealth probably afforded him private tutors inhis early childhood. When he turned 11 years old,Cavendish was sent to study at Dr. Newcome’sSchool in Hackney, England. At 18 he was offto Cambridge, where he enrolled in St. Peter’sCollege.

After dropping out of Cambridge during hisfourth year and taking a traditional tour ofEurope with his brother, he inherited a fortunethat made him one of the wealthiest men inEngland. However, instead of behaving as onemight expect after such good luck, Cavendishbecame a virtual recluse for the rest of his life,living frugally in London and immersing himselfin scientific studies.

As strange and solitary as Cavendish was,he was an extraordinary scientist. One of his firstaccomplishments occurred in 1766 with the dis-covery of hydrogen. Known as “flammable air”and studied by others for a century before him,this gas was often also called “phlogiston,” anancient term for a nonexistent element that,prior to the discovery of oxygen, was thought tobe released as a product of combustion. ButCavendish was the first to measure its specificgravity and posited that hydrogen was a differ-ent gaseous substance from ordinary air, whosecomponents he subsequently analyzed as com-posed of nitrogen and oxygen in an approximate4:1 ratio.

Cavendish, Henry 79

The discovery of water, or rather its com-position, is also due to Cavendish’s experiments.In 1781 he discovered that water was composedof hydrogen, his “flammable air” discovery, andoxygen, which he determined by burning thetwo chemicals together, in the proper ratio nowknown as H2O. He was the first person to hearthe famous “POP!” that high school chemistrystudents experience when they hold a Bunsenburner to the mouth of the bottle of collectedhydrogen.

Cavendish wrote, “. . . on applying the lightedpaper to the mouth of the bottle . . . with 3 partsof flammable air to 7 of common air, there wasa very loud noise.” Then, when he combined thehydrogen with the oxygen, he produced water,leading him to reverse the process and prove onceand for all that water was composed of “flamma-ble air” and oxygen. As Cavendish described it,“By the experiments . . . it appeared that whenflammable and common air are exploded in aproper proportion, almost all of the flammableair and near one-fifth of the common air losetheir elasticity and are condensed into dew.”

While he was at it, Cavendish also notedthat the water’s weight was equal to the weightof the gases. French chemist Antoine-Laurentde Lavoisier (1743–94) named the new gas hy-drogen—Greek for “water-former.” Cavendisheventually calculated the composition of air tobe 79.167 percent “phlogisticated air” (nowknown as nitrogen) and 20.833 percent “de-phlogisticated air” (oxygen), but also estab-lished that 1⁄120 was a mysterious third gas,which 100 years later was discovered to be ar-gon in 1894 by the Scotsman Sir William Ramsey(1852–1916) at University College, London.

Such chemistry discoveries ultimately sup-ported his work in astronomy. Cavendish was thefirst to determine SIR ISAAC NEWTON’s “gravita-tional constant,” which he published in 1798as “Experiments to Determine the Density ofthe Earth,” one of his few published papers inhis lifetime. His work over a two-year period

resulted in accurately measuring the mass anddensity of the earth as 5.48 times that of water,stunningly close to the 5.5268 calculated bymodern techniques. This constant of propor-tionality used in Newton’s Law of UniversalGravitation, or G, was found to be 6.67 3 10–11

newtons between two objects with a mass of onekilogram each at a distance from each other ofone meter. Cavendish calculated this constantmeasuring the gravitational force between twometal spheres. Knowing G permitted the deter-mination of the Earth’s mass, and subsequentlythe mass of the Sun and planets.

Cavendish also dabbled in electrical meas-urements, sometimes measuring the strength ofan electrical current by shocking himself andthen comparing the levels of pain he experi-enced. Some of his experiments investigated thephenomenon of capacitance, and he came veryclose to formulating what was to become Ohm’sLaw. Cavendish’s work in electricity was redis-covered and published after his death by JamesClerk Maxwell (1831–79), the scientist knownfor discovering electromagnetism.

Although he himself admitted to having “asingular love of solitariness,” Cavendish did haveone social function in his life, albeit a scientificsocial function, that he religiously attended—hewas a member of the Royal Society and is re-ported to have rarely missed the weekly dinnermeetings. But while his scientific discoverieswere highly regarded by his contemporaries,even they considered him an extremely oddman. It could have been due to the way hedressed. Although a man of amazing wealth,Cavendish wore the same clothes nearly everyday—an outfit that consisted of “a crumpled vi-olet suit” that was in style during the previouscentury, with ruffled cuffs and a high ruffled col-lar, topped off by his equally-out-of-style trade-mark three-cornered hat. Or perhaps it was theway he talked, or more accurately did not talk,that put off his contemporaries. When hespoke, which was rare even at the Royal Society

80 Chandrasekhar, Subrahmanyan

meetings, his voice was described as shrill andhigh, and he was so shy that he stammered andcommunicated with great difficulty. Completelyinept in dealing with women, Cavendish com-municated with his household staff strictly usinghandwritten notes, and the women who workedfor him were ordered to stay completely out ofhis sight under threat of being fired.

Social skills aside, his brilliance was still ableto shine despite his lack of verbal and writtencommunication with his colleagues. Cavendishpublished fewer than 20 papers in his 50-yearcareer, but his first, titled “Factitious Airs” andpublished in 1766, earned him the RoyalSociety’s Copley Medal. He was a member of theRoyal Society from 1760 until his death. Nevermarried, Cavendish’s sole social contact was din-ing with other Royal Society members. LordHenry Broughman (1778–1868), a fellow mem-ber who eventually became Lord Chancellorof England, once commented that Cavendish“probably uttered fewer words in the course ofhis life than any man who ever lived to fourscoreyears, not at all excepting the monks of LaTrappe.” Cavendish was a scientist to the end.According to Broughman, Cavendish wanted tobe left alone on his deathbed, because he did notwant any interruptions while he observed andrecorded the progress of the disease that was run-ning through his body. Cavendish died alone athome, except for his staff-in-hiding, on March10, 1810. The famous Cavendish Laboratory atCambridge University is named in his honor, asis a crater on the Moon.

5 Chandrasekhar, Subrahmanyan(Chandra)(1910–1995)Indian, Naturalized AmericanAstrophysicist

Subrahmanyan Chandrasekhar was known formost of his scientific life simply as “Chandra.”

He was born in Lahore, southern India, then partof British colonial India, to an educated family.His uncle was a Nobel laureate and his fatherwas an executive for the Indian railway systemwho moved the family to Madras when Chandrawas six.

Chandra was an exceptionally brilliant stu-dent from the start. At the tender age of 15, hewas admitted to the most prestigious college inMadras, the Presidency College, where he en-rolled in the school’s physics honors program,graduating with a bachelor’s degree in theoreti-cal physics at the top of his class. During thisprogram he read Ralph H. Fowler’s (1889–1944)early work at Cambridge University’s TrinityCollege on “white dwarfs,” stars that haveburned off their internal supply of hydrogen andhave collapsed into themselves as intensely hot,highly massive, but very small, remnant stars.This subject fascinated him, and at 18 years oldChandra wrote his first scientific paper andsent it to Fowler, who liked it so much he sentit to the Royal Society. It was published as“Compton Scattering and the New Statistics”in the Proceedings of the Royal Society. It was be-cause of this paper that upon graduationChandra was accepted as a research student atCambridge after winning an Indian governmentscholarship.

When Chandra left Bombay on the voyageto England, he became seasick and, confined tohis stateroom, worked out new calculationsbased on Fowler’s work and his own training inrelativity theory. By the time the ship dockedtwo weeks later, Chandra had worked out hisfirst suspicion that there was an upper limit tothe mass of a white dwarf, a concept that wentcompletely against the prevailing theory at thetime. When he put forth his new theory atCambridge, the country’s two leading astro-physicists, SIR ARTHUR STANLEY EDDINGTON andEdward A. Milne (1896–1950), dismissed hisproposition as impossible, and Eddington in par-ticular publicly rejected Chandra’s conclusions.

Chandrasekhar, Subrahmanyan 81

Chandra’s theory was essentially this: Duringits evolution, a star goes through a stage knownas a “red giant,” in which its radius may be hun-dreds of times its original size; after this the stargradually implodes, even if it were once a 7- or10-solar mass, into a mass lower than Chandra’s1.4 solar mass limit. At this stage no more nu-clear energy can be gained, and when the newdwarf star’s iron core grows to the 1.4 solar massnumber, it collapses by gravitation again.

Chandra continued to work on his theoryand, after receiving his Ph.D., was elected aFellow of Trinity College. After undertakingmore complete calculations, he confirmed hisearlier result and concluded that the mass of awhite dwarf had an upper limit of 1.4 solar mass.At age 25, he was then invited to present hisresults in a lecture in 1935 at the RoyalAstronomical Society. When he did, Eddingtonagain publicly rejected Chandra’s results, andone report quotes him as saying, “I think thereshould be a law of nature to prevent a star frombehaving in this absurd way.” Scientific ob-servers of the day realized that Eddington’s life’swork had been to prove that every star, regard-less of its mass, had a stable configuration andChandra’s contention, if valid, would destroythat proof.

Nevertheless Chandra was devastated. Hefinally appealed to some respected physicists heknew—Léon Rosenfeld (1904–74), Niels Bohr(1885–1962), and Wolfgang Pauli (1900–58)—who unanimously made it known to the scien-tific community that they heartily agreed withChandra’s conclusions. His upper limit of 1.4 so-lar masses is known today as “Chandrasekhar’sLimit.” However, it is generally agreed in sci-entific circles that the monkey wrench throwninto the discussion by Eddington and Milnewas responsible for Chandra having to wait 50years before winning the Nobel Prize in physicsin 1983. It apparently made it difficult forChandra to acquire any kind of prestigiousposition in England, and the beginnings of

political unrest in his native India made re-turning home imprudent. Thus, he accepted anoffer from Otto Struve (1897–1963) to join thefaculty at the Yerkes Observatory of the Universityof Chicago in 1937. Before reporting, however,he journeyed back to India to marry LalithaDoraiswamy, a former schoolmate in the physicsprogram at Presidency College in Madras. Lalithawas then working in the Bangalore laboratory ofChandra’s uncle, the physics Nobel laureateChandrasekhara Venkata Raman (1888–1970).

Chandra would remain at the University ofChicago for the rest of his life, becomingMorton D. Hall Distinguished Service Professorin Astronomy and Astrophysics in 1952. Whileat Chicago, he delved into theoretical work onstellar interiors, and became keenly interested inthe gravitational frictional drag on a star pass-ing through a tenuous cloud of stars, using such“drag” to determine the ages of globular clusters.He also developed equations for interactinggravitational waves, and is responsible for de-veloping the post-Newtonian approximationthat has become the standard formal approachto calculating the gravitational waves from dy-namic systems of massive particles.

Chandra was a great supporter of MohandasGandhi, but when World War II broke out hefelt that helping the cause of victory overHitler’s Nazi Germany was his most importantduty. His contribution to the war effort wasworking half time at the Aberdeen ProvingGround on shock waves, and only lengthy clear-ance problems prevented him from accepting aninvitation to join the Manhattan Project at LosAlamos. He became an American citizen in1953.

While at Chicago, Chandra published sixbooks and numerous scientific papers, each ofwhich is considered definitive in its field: AnIntroduction to the Study of Stellar Structure(1939); Principles of Stellar Dynamics (1943);Radiative Transfer (1950); Hydrodynamic andHydromagnetic Stability (1961); Ellipsoidal Figures

82 Charlier, Carl Vilhelm Ludvig

of Equilibrium (1968); and The MathematicalTheory of Black Holes (1983).

He and Eddington eventually patched uptheir differences, and Eddington was instrumen-tal in Chandra’s 1944 election to the RoyalSociety. Eddington died that year, and in anobituary speech, Chandra ranked Eddingtonnext to KARL SCHWARZSCHILD as the greatest as-tronomer of his time. In 1962 Chandra receivedthe Royal Society’s coveted Royal Medal. In1966 he received the National Medal of Science.He was also editor of the Astrophysical Journalfrom 1952 to 1971, taking it from a relativelysmall and unnoticed university journal to the in-ternationally respected journal of the AmericanAstronomical Society.

Chandra also developed an intense interestin literature and music, and was considered bymany authorities to be a master of the Englishlanguage. His 1987 book, Truth and Beauty, is acollection of essays exploring the similarities inmotivation and aesthetic rewards of artists andscientists.

At his death in 1995, he was praised by stu-dents, associates, and world scientific leaders aspossibly the greatest astrophysicist of the 20thcentury. NASA renamed its Advanced X-rayAstrophysics Facility (AXAF) the Chandra X-ray Observatory in honor of him, and launchedit in the space shuttle Columbia in 1999 to studyfaint sources in X-rays in crowded fields from anelliptical high-earth orbit.

5 Charlier, Carl Vilhelm Ludvig(1862–1934)SwedishAstronomer, Mathematician

Carl Vilhelm Ludvig Charlier was born April 1,1862, in Ostersund, the capital of Jamtland, aprovince in northern Sweden. He was the sonof Emanuel Charlier, a government official, andAurora Kristina Hollstein. He attended the

local high school and in 1881 entered the pres-tigious University of Uppsala, the oldest uni-versity in the Nordic countries, founded in1477. There, he came under the influence ofProfessor Herman Shultz, then director of theUppsala Observatory, becoming an assistant inhis third year, and he studied theoretical math-ematics and astronomy using the observatory’s9-inch refractor.

Charlier received his Ph.D. in 1887 with adissertation on Jupiter’s effect on the orbit of mi-nor planet 17 Thetis. A year later he became anassistant at nearby Stockholm Observatory, un-der the direction of Johan A. H. Gylden, aleader in celestial mechanics research. However,Charlier brought his mathematical expertise tomore practical problems, such as the new appli-cation of photography to astronomical observa-tions. His initial task was to develop a practicalmethod for photographic photometry. At Uppsalahe had gained some experience in the use ofa visual photometer, and at the StockholmObservatory he used a small photographic tele-scope to observe the Pleiades group of stars.Using a micrometer, he measured the diametersof the various star disks on his plates and estab-lished a formula relating the image diameters tothe photometric magnitudes of the brighterPleiades stars. This formula enabled him to be-come the first observer to determine the magni-tudes of the fainter Pleiades stars. At the time,his paper describing his Pleiades work was con-sidered a groundbreaking contribution and wasselected by the Astronomische Gesellschaft fordedication of the Pulkowa Observatory on its50th anniversary.

After two years at Stockholm Observatory,Charlier went back to Uppsala, where from 1890to 1897 he was chief assistant. During this timea new photographic refractor was installed andCharlier became interested in the theory ofastronomical and photographic lens combina-tions. He published many papers on the de-velopment of an achromatic objective lens

Clark, Alvan Graham 83

comprised of two lenses of the same glass mate-rial instead of the current standard of flint andcrown glass.

In 1897, at age 35, Charlier received thehighest position in Swedish astronomy: profes-sor of astronomy and director of the observatoryat the University of Lund, a position he held for30 years. One of his accomplishments during thistenure was to establish two series of observa-tory publications, published under the nameMeddelanden. More than 150 issues were printedunder his direction, comprising 10 volumes. Hecontinued his work in celestial mechanics atLund. It is noteworthy that, while Charlier’searly works were published in Swedish, he even-tually also wrote his technical papers and booksin German, French, and English. Writing scien-tific papers in four different languages is quitepossibly a feat achieved by no other astronomerin history.

The contributions Charlier made to theo-retical astronomy and statistical theory aremany. Chief among them are a study on the ef-fect on asteroid orbits of secular perturbations,that is, the slow progressive changes in plane-tary orbits, and a study of the rotation of plan-ets around their axes. Also while at Lund,Charlier brought his knowledge of mathemati-cal statistics to the field of astronomy. Charlierdemonstrated that all distribution laws in naturecan be represented by one of two classes of er-ror functions. He was called upon to test this ap-plication in other fields as well, such as biology,medicine, and population statistics. The courseshe taught at the University of Lund led to theestablishment of a separate chair for mathematicalstatistics.

Charlier also made extensive statistical stud-ies of the distributions and motions of stars nearthe Sun, and showed that hotter stars and galax-ies form a flattened system. His hierarchicalmodel of the universe proposed that it is madeup of a successive series of higher and highersystems.

Charlier became a member of the Astro-nomische Gesellschaft in 1887, and in 1904 waselected to the board of directors, on which heserved for 13 years. He was awarded the WatsonGold Medal of the National Academy ofSciences in 1924; the Memorial Medal of theRoyal Physiographic Society at Lund, also in1924; an honorary membership in the AmericanAstronomical Society in 1921; and in 1933 wasawarded the prestigious Bruce Gold Medal of theAstronomical Society of the Pacific. In his re-tirement he translated SIR ISAAC NEWTON’sPrincipia Mathematica Philosophiae Naturalis intoSwedish, and he wrote a French textbook onthe applications of statistics to astronomy.

Charlier was one of the most influentialteachers of astronomers and statisticians, and el-evated the University of Lund to a prominentposition in the world astronomical community.Among his students were Gustav Stromberg(1882–1962), who did important spectroscopicresearch at the Lick Observatory on MountWilson, and Karl Malmquist (1893–1982), whodescribed analysis pitfalls of brighter object biasin astronomical surveys.

Charlier was stricken by an apoplectic eventin 1932, and he died at Lund on November 5,1934, leaving his widow Siri Dorotea Leissnerand five daughters.

5 Clark, Alvan Graham(1832–1897)AmericanAstronomer, Lensmaker

Alvan Graham Clark made several of the finesttelescope lenses ever produced. Clark was bornin Fall River, Massachusetts, in 1832. His father,Alvan Clark, made instruments for a living.Alvan Senior had very definite plans about hisbusiness life, and in 1846 he opened a com-pany, Alvan Clark & Sons, that specialized inmaking lenses for telescopes. Alvan Junior

84 Clark, Alvan Graham

wanted to be an artist, specifically a portraitpainter, but at the age of 20 he joined hisfather’s firm in Cambridgeport and learned thelens-grinding art, eventually becoming the firm’schief optician.

It was while Clark was testing one of his cre-ations, a new 18-inch lens in a telescope he hadbuilt for the Dearborn Observatory in Chicago(now Northwestern University’s observatory),that he made his first astronomical discovery. Heturned the instrument toward Sirius, the DogStar, and observed for the first time a compan-ion star. This star had been predicted 18 yearsearlier by astronomer FRIEDRICH WILHELM BESSEL,who had observed Sirius for more than 10 yearsand concluded that it had an unseen compan-ion, but now Clark confirmed its existence.Sirius B is a white dwarf star—an extremely hotbut very small star—the first white dwarf to everbe discovered. For his achievement, Clark washonored with the Lalande Prize of the FrenchAcademy of Science. As a companion star tothe Dog Star, Sirius B is nicknamed “the Pup.”

But Clark’s most significant contributions toastronomy were the famous and coveted lenseshe built for the major observatories and as-tronomers of the time. He built five significantlenses in his lifetime, and each of these impor-tant lenses, bigger than the previous, becamethe largest refractor available, setting new worldrecords when they were installed.

In 1896 Clark built the 24-inch lens for theLowell Observatory in Flagstaff, Arizona. Thistelescope is still on display in the “weddingcake” dome at the observatory. PERCIVAL LOWELL

(1855–1916), who was convinced that there wasa planet beyond Neptune, funded three projectsfor the search. During the third project, onFebruary 18, 1930, a young astronomer namedCLYDE WILLIAM TOMBAUGH discovered theplanet on his photographic plates. He is the onlyAmerican to discover a planet. His plates ofPluto are on display at the observatory near thetelescope.

In 1861 SIMON NEWCOMB was appointed tothe Naval Observatory, which had been foundedin 1830 as the Depot of Charts and Instruments,in Washington, D.C. He supervised Clark inbuilding a new 26-inch refractor for the obser-vatory, the largest refractor ever made. In 1877ASAPH HALL used this telescope to discoverDeimos and Phobos, the two moons of Mars.The telescope is still in use today to monitordouble stars, and the observatory reports that itsoptics are “phenomenally good.”

In 1878 a new 30-inch refractor was builtfor Polkovo Observatory near Leningrad,Russia, which was used some years later by theRussian astrophysicist Gavriil Adrianovich Tikhov(1875–1960), the founder of astrobiology, tostudy the Martian terrain. The telescope wasdestroyed during World War II.

The 36-inch refractor built for the LickObservatory in Mount Hamilton, California,cost approximately $180,000 when it was in-stalled in 1888 in the large dome at the obser-vatory, considered the most advanced at thetime. This was the first time an observatory hadbeen built for its favorable location to observerather than its proximity to a university. EDWARD

EMERSON BARNARD made many of his famousobservations on this telescope, including his dis-covery of the fifth moon of Jupiter. The tele-scope is still in operation today.

The 40-inch refracting telescope at theUniversity of Chicago’s Yerkes Observatory inWilliams Bay, Wisconsin, remains the largestrefractor ever made. The lens was installed intothe 63-foot (19.2 m) telescope on May 20,1897, and operated in a small but significantceremony the next evening by GEORGE ELLERY

HALE, who pointed the telescope at Jupiterand showed guests what the planet looks likeat 400x the magnification of the naked eye.Some of the most famous astronomers haveused the 40-inch Yerkes telescope to maketheir observations and discoveries, includingBarnard, Hale, GERARD PETER KUIPER, and

Clausius, Rudolf Julius Emmanuel 85

SUBRAHMANYAN CHANDRASEKHAR. This was thelast lens made by Clark, just before his death.

Because there is an optical limit to usinglenses larger than 40 inches, scientists in thatera began using mirrors in reflecting telescopesto achieve greater magnifications, which is whythe Yerkes lens is still, more than a centurylater, the largest refracting telescope in theworld.

Clark discovered 16 more double stars be-fore he died in 1897, and most of his discover-ies came by testing lenses he had made forother people or institutions. Eventually, re-fracting telescopes incorporating lenses madeby Clark would make some of the major astro-nomical discoveries of the late 19th and 20thcenturies.

5 Clausius, Rudolf Julius Emmanuel(1822–1888)GermanPhysicist

By introducing the concept of entropy in 1865,Rudolf Clausius completed his development ofthe first comprehensive understanding of thesecond law of thermodynamics—a scientific featthat allowed 19th-century cosmologists to pos-tulate a future condition (end state) they called“heat death of the universe.”

A German theoretical physicist, Clausiuswas born on January 2, 1822, in Köslin, Prussia(now Koszalin, Poland). His father, the ReverendC. E. G. Clausius, served as a member of theRoyal Government School Board and taughtat a small private school where Clausius at-tended primary school. In 1840 he entered theUniversity of Berlin as a history major, butemerged in 1844 with his degree in mathemat-ics and physics. After graduation Clausius taughtmathematics and physics at the Frederic-WerderGymnasium (secondary school), while pursuinghis graduate degree. In 1848 he received his

doctorate in mathematical physics from theUniversity of Halle. In 1850 he accepted a po-sition as a professor at the Royal Artillery andEngineering School in Berlin.

In 1850 Clausius also published his first andwhat is now regarded as his most important pa-per discussing the mechanical theory of heat.The famous paper, entitled “Uber die bewegendeKraft der Wärmer” (“On the Motive Force ofHeat”), provided the first unambiguous state-ment of the Second Law of Thermodynamics. Inthis paper, read at the Berlin Academy onFebruary 18, 1850, and then published in itsAnnalen der Physik (Annals of physics) later that

Through his work on the second law of thermo-dynamics and his development of the concept ofentropy, the German theoretical physicist RudolfClausius had a major impact on 19th-centurycosmology. He concluded that the entropy of theuniverse was striving to achieve a maximum valueunder the laws of thermodynamics. The end conditionwould be what he called “the heat death” of theuniverse—a state of complete temperature equilibriumwith no energy available to perform any useful work.(AIP Emilio Segrè Visual Archives)

86 Clausius, Rudolf Julius Emmanuel

year, Clausius built upon the heat engine theoryof the French engineer and physicist, SadiCarnot (1796–1832), and introduced his versionof second law of thermodynamics in a simple,yet important statement: “Heat does not spon-taneously flow from a colder body to a warmerbody.” While there is one basic statement of theFirst Law of Thermodynamics, namely, theconservation-of-energy principle, there are quiteliterally several hundred different, yet equallyappropriate, statements of the second law. Clau-sius’s perceptive statements and insights, as ex-pressed in 1850, lead the long and interestingparade of second law statements. This particularpaper is often regarded as the foundation ofclassical thermodynamics.

However, in the 19th century many physi-cists, including the famous British naturalphilosopher William Thomson Kelvin, firstbaron of Largs (1824–1907), were also grapplingwith the nature of heat and developing basicmathematical relationships to describe and pre-dict how thermal energy flows through the uni-verse and is transformed into mechanical work.Clausius is generally given credit as the personwho most clearly described the nature, role, andimportance of the second law—although others,like Lord Kelvin, were simultaneously involvedin the overall quest for understanding the me-chanics of thermophysics.

Between 1850 and 1865 Clausius publisheda number of other papers dealing with mathe-matical statements of the second law of ther-modynamics. This effort climaxed in 1865, whenhe introduced the concept of entropy as a ther-modynamic property to describe the availabilityof thermal energy (heat) for performing me-chanical work. In his paper of 1865, Clausiusconsidered the universe to be a closed system(that is, a system that has neither energy normass flowing across its boundary) and then suc-cinctly tied together the first and second laws ofthermodynamics with the following elegantstatement: “The energy of the universe is constant

(first law principle); the entropy of the universestrives to reach a maximum value (second lawprinciple).”

By introducing the concept of entropy in1865, Clausius provided scientists with a con-venient mathematical way to understand andexpress the second law of thermodynamics. Inaddition to its tremendous impact on classicalthermodynamics, his pioneering work also hadan enormous impact on 19th-century cosmology.As previously stated, Clausius assumed that thetotal energy of the universe (taken as a closedsystem) was constant, so the entropy of the uni-verse must then strive to achieve a maximumvalue in accordance with the laws of thermody-namics. According to this model, the end stateof the universe is one of complete temperatureequilibrium, with no energy available to performany useful work. Cosmologists call this condi-tion the heat death of the universe.

In 1855 Clausius accepted a position at theUniversity of Zurich and in 1859 married his firstwife, Adelheid Rimpam. She bore him six chil-dren, but died in 1875 giving birth to the cou-ple’s last child. While he enjoyed teaching inZurich, he longed for Germany and returned tohis homeland in 1867 to accept a professorshipat the University of Würzburg. He moved on tobecome a professor of physics at the Universityof Bonn in 1869, where he taught for the rest ofhis life. At almost 50 years of age, he organizedsome of his students into a volunteer ambulancecorps for duty in the Franco-Prussian War(1870–71). Clausius was wounded in action andreceived the Iron Cross in 1871 for his servicesto the German army. He remarried in 1886, andhis second wife, Sophie Stack, bore him a son.He continued to teach until his death on August24, 1888, in Bonn, Germany.

Despite a certain amount of nationalisticallyinspired international controversy over who de-served credit for developing the second law ofthermodynamics, Clausius left a great legacy intheoretical physics and earned the recognition

Compton, Arthur Holly 87

of his fellow scientists from throughout Europe.He was elected as a foreign fellow of the RoyalSociety of London in 1868 and received thatsociety’s prestigious Copley Medal in 1879. Healso was awarded the Huygens Medal in 1870by the Holland Academy of Sciences and thePoncelet Prize in 1883 by the French Academyof Sciences. The University of Würzburg be-stowed an honorary doctorate upon him in1882.

5 Compton, Arthur Holly(1892–1962)AmericanPhysicist

Arthur Holly Compton was one of the pioneersof high-energy physics. In 1927 he shared theNobel Prize in physics for his investigation of thescattering of high-energy photons by electrons—an important phenomenon called the “Comptoneffect.” His research efforts in 1923 provided thefirst experimental evidence that electromag-netic radiation possessed both particle-like andwavelike properties. Compton’s important dis-covery made quantum physics credible. In the1990s the National Aeronautics and SpaceAdministration (NASA) named its advancedhigh-energy astrophysics spacecraft the ComptonGamma Ray Observatory (CGRO) after him.

A. Compton was born on September 10,1892, into a distinguished intellectual family inWooster, Ohio. Elias Compton, his father, was aprofessor at Wooster College, and his olderbrother, Karl, studied physics and went on tobecome the president of the MassachusettsInstitute of Technology. As a youth, Comptonexperienced two very strong influences from hisfamily environment: a deep sense of religiousservice and the noble nature of intellectual work.While he was an undergraduate at WoosterCollege, he seriously considered becoming aChristian missionary. But his father convinced

him that, because of his talent and intellect, hecould be of far greater service to the humanrace as an outstanding scientist. His olderbrother also helped persuade him to study sci-ence, and in the process changed the course ofmodern physics by introducing him to the studyof X-rays.

Compton carefully weighed his career op-tions and then followed his family’s advice byselecting a career of service in physics. Hecompleted his undergraduate degree at Wooster

The Nobel laureate physicist Arthur Holly Comptonidentified a special high-energy photon scatteringphenomenon. This phenomenon, now called Comptonscattering, has become the foundational principlebehind many of the gamma ray detection techniquesused in modern high-energy astrophysics. Comptonshared the Nobel Prize in physics in 1927 for hisdiscovery. To further honor his achievements, in 1991NASA named its large astrophysics laboratory theCompton Gamma Ray Observatory (CGRO). (Photograph by Moffett Studio, AIP Emilio SegrèVisual Archives)

88 Compton, Arthur Holly

College in 1913 and joined his older brother atPrinceton. He received his master of arts degreein 1914 and his Ph.D. degree in 1916 fromPrinceton University. For his doctoral research,Compton studied the angular distribution of X-rays reflected from crystals. Upon graduation,he married Betty McCloskey, an undergraduateclassmate from Wooster College. The couple hadtwo sons: Arthur Allen and John Joseph.

After spending a year as a physics instructorat the University of Minnesota, Compton workedfor two years in Pittsburgh, Pennsylvania, as anengineering physicist with the WestinghouseLamp Company. Then, in 1919, he receivedone of the first National Research Council fel-lowships awarded by the U.S. government.Compton used his fellowship to study gammaray scattering phenomena at Baron ErnestRutherford’s (1871–1937) Cavendish Laboratoryin England. While working with Rutherford, heverified the puzzling results obtained by otherphysicists—namely, that gamma rays experi-enced a variation in wavelength as a functionof scattering angle.

The following year, Compton returned tothe United States to accept a position as headof the department of physics at WashingtonUniversity in Saint Louis, Missouri. There,working with X-rays, he resumed his investiga-tion of the puzzling mystery of photon scatter-ing and wavelength change. By 1922 his exper-iments revealed that there definitely was ameasurable shift of X-ray (photon) wavelengthwith scattering angle—a phenomenon nowcalled the “Compton effect.” He applied specialrelativity and quantum mechanics to explain theresults, presented in his famous paper “AQuantum Theory of the Scattering of X-rays byLight Elements,” which appeared in the May1923 issue of The Physical Review. In 1927Compton shared the Nobel Prize in physics withCharles Wilson (1869–1959), for his pioneeringwork on the scattering of high-energy photonsby electrons.

It was Wilson’s cloud chamber that helpedverify the behavior of Compton’s X-ray scatteredrecoiling electrons. Telltale cloud tracks of re-coiling electrons provided corroborating evidenceof the particle-like behavior of electromagneticradiation. Compton’s precise experiments de-picted the increase in wavelength of X-rays dueto the scattering of the incident radiation by freeelectrons. Since his results implied that the scat-tered X-ray photons had less energy than theoriginal X-ray photons, Compton became thefirst scientist to experimentally demonstratethe particle-like “quantum” nature of electro-magnetic waves. His book Secondary RadiationsProduced by X-Rays (1922) described much ofthis important research and his experimentalprocedures. The discovery of the Compton effectserved as the technical catalyst for the accept-ance and rapid development of quantum me-chanics in the 1920s and 1930s.

The Compton effect is the physical principlebehind many of the advanced X-ray and gammaray detection techniques used in contemporaryhigh-energy astrophysics. In recognition of hisuniquely important contributions to modern as-tronomy, NASA named a large orbiting high-energy astrophysics observatory, the ComptonGamma Ray Observatory (CGRO), in his honor.NASA’s space shuttle placed this important sci-entific spacecraft into orbit around Earth in April1991. Its suite of gamma ray instruments operatedsuccessfully until June 2000 and provided scien-tists with unique astrophysical data in the gammaray portion of the electromagnetic spectrum—animportant spectral region not observable byinstruments located on Earth’s surface.

In 1923 Compton became a physics profes-sor at the University of Chicago. Once settledin at the new campus, he resumed his world-changing research with X-rays. An excellentteacher and experimenter, he wrote the 1926textbook X-Rays and Electrons to summarize andpropagate his pioneering research experiences.From 1930 to 1940 Compton led a worldwide

Copernicus, Nicolas 89

scientific study to measure the intensity of cos-mic rays and to determine any geographic varia-tion in their intensity. His precise measurementsshowed that cosmic ray intensity actually corre-lated with geomagnetic latitude rather than ge-ographic latitude. Compton’s results impliedthat cosmic rays were very energetic chargedparticles interacting with Earth’s magnetic field.His pre–space age efforts became a major con-tribution to space physics and stimulated a greatdeal of scientific interest in understanding theEarth’s magnetosphere—an interest that gaverise to many of the early satellite payloads, in-cluding JAMES ALFRED VAN ALLEN’s instrumentson the Explorer I satellite.

During World War II Compton played amajor role in the development and use of theatomic bomb. He served as a senior scientificadviser and was also the director of theManhattan Project’s Metallurgical Laboratoryat the University of Chicago. Under Compton’sleadership in the “Met Lab” program, the bril-liant Italian-American physicist Enrico Fermi(1901–54) was able to construct and operate theworld’s first nuclear reactor on December 2,1942. This successful uranium-graphite reactor,called Chicago Pile One, became the technicalancestor for the large plutonium-production reactors built at Hanford, Washington. TheHanford reactors produced the plutonium usedin the world’s first atomic explosion, the Trinitydevice detonated in southern New Mexico on July 16, 1945, and also in the Fat Man atomic weapon dropped on Nagasaki, Japan, onAugust 9, 1945. Compton described his wartimerole and experiences in the 1956 book AtomicQuest—A Personal Narrative.

Following World War II, he put aside physicsresearch and followed his family’s tradition ofChristian service to education by accepting theposition of chancellor at Washington Universityin St. Louis, Missouri. He served the universityas its chancellor until 1953 and then contin-ued there as a professor of natural philosophy,

until failing health forced him to retire in 1961.He died in Berkeley, California, on March 15,1962.

Compton received numerous awards through-out his illustrious scientific career. In addition tothe Nobel Prize in physics, he also received theAmerican Academy of Arts and SciencesRumford Gold Medal in 1927. The RadiologicalSociety of North America presented him withits Gold Medal in 1928. The Royal Society inLondon bestowed its Hughes Medal on him in1940. That same year, he also received theFranklin Medal from the Benjamin FranklinInstitute in Philadelphia, Pennsylvania. Comptonserved as the president of the American PhysicalSociety (1934) and the president of the AmericanAssociation for the Advancement of Science(1942).

5 Copernicus, Nicolas (Mikolaj Kopernik, Niklas Koppernigk, Nicolaus Copernicus, Nicholas Copernicus)(1473–1543)PolishAstronomer

Revolutionary ideas gave Nicolas Copernicus hispermanent place of prestige in the field of as-tronomy. His proposal that the Sun, rather thanthe Earth, was the center of our universe foreverchanged how we view ourselves in the cosmos.But Copernicus was neither a revolutionary noran astronomer by trade. And his ideas of thestructure of our solar system, called a heliocen-tric system, were ones he discovered as a studentin his late 20s at the University of Cracow, study-ing astronomy and ancient philosophy, amongother subjects.

Yet it was his interpretation of what to dowith these radical theories, and his originalthoughts surrounding his discoveries, that leadto revolutionary ideas supported by the likesof GIORDANO BRUNO, JOHANNES KEPLER, and

90 Copernicus, Nicolas

GALILEO GALILEI, all of whom suffered at thehands of the Roman Catholic Church for sup-porting Copernicus’s published work, which wasironically dedicated to, and gratefully receivedby, the pope.

Born in Thorn, Poland, in 1473, theyounger of two brothers, Copernicus was takeninto the care of his uncle at age 10 after hisfather’s death. This man, Lucas Waczenrode,with whom Copernicus would ultimately spendmost of his life, was dedicated to two things:serving the Catholic Church and providing hisyoung nephews with an education.

Copernicus’s university studies began at theUniversity of Cracow, in the capital of Poland,where art, mathematics, astrology, and astron-omy were part of his course of study. In 1496 hewent to Italy, taking up studies in Bologna,Padua, and Ferrara, mostly in canon law andmedicine. In 1501, when he began his studiesin medicine at the University of Padua,Copernicus took courses in Greek and Latin.In addition to learning new languages, he wasfor the first time exposed to the writings of an-cient philosophers. As with any medical stu-dent of the time, he also undertook morecourses in astronomy and astrology. The expo-sure to philosophy and astronomy would ulti-mately have the biggest impact on his contri-bution to science.

He returned to Poland in 1503, rejoining hisuncle, who had risen through the ranks of theCatholic Church to the position of bishop ofErmeland. Copernicus, now 30 years old, ac-cepted a position in the Chapter of Frauenberg,and in addition to his duties as canon becamehis uncle’s personal physician. His life was to beone of dedication to the church, even to thepoint of ending a relationship with his house-keeper when the church told him to do so.Astronomy was something he worked on in hisspare time.

It was sometime around 1512 that Copernicuswrote his Commentariolus, a “short comment”outlining his thoughts on the order of the uni-verse. This new world system was based onPTOLEMY’s geocentric system, with a twist—instead of the Earth being the center of theuniverse, Copernicus theorized that everythingrevolved around the Sun. He also believed thatthe Earth rotated on its own axis, and he usedthe rotation of the Earth and its revolutionaround the Sun to explain the idea of planetsspinning in retrograde.

Seventeen centuries earlier, according tothe work of Archimedes (287–212 B.C.E.), thePythagorean ARISTARCHUS OF SAMOS had first

The 16th-century Polish astronomer and churchofficial Nicolas Copernicus launched the scientificrevolution with the deathbed publication of his book,On the Revolution of Heavenly Spheres in 1543. Byadvocating heliocentric cosmology, Copernicushelped overthrow the Ptolemaic system and nearlytwo millennia of mistaken adherence to the Earth-centered cosmology of the ancient Greekphilosophers. (AIP Emilio Segrè Visual Archives,T.J.J. See Collection)

Copernicus, Nicolas 91

proposed that the Earth rotated on its axis andrevolved around the Sun. His contemporariesthought his ideas were absurd, if not blasphemous,based on simple observation of everything thatwas “natural.” Ptolemy’s geocentric model was up-held as the one true system that “worked,” eventhough it was extremely complicated and veryflawed. Common practice throughout the cen-turies was to construct excuses to prove thatPtolemy’s model was right. This was a normal partof science that became referred to as “saving theappearances” that the geocentric system ruled.

When Copernicus worked out the sameideas proposed by Aristarchus, he was the last tothink that he was contradicting Ptolemy. He feltthat his theories were an extension of Ptolemy’swork, offering some simplicity and clarity. Heworked on this process of clarification, makingcomputations and creating new tables, for a fewdecades. He mostly kept his Commentariolus tohimself, sharing it only with a few good friends,who also happened to be members of the church.Surprisingly, the Catholics he entrusted withhis work applauded it, and repeatedly urgedhim to publish his ideas, which he declined todo for several years. But word of his findingstraveled, eventually making its way to a youngmathematician in Wittenberg named Rheticus(1514–74), who in 1539 traveled to meet theman who had done what had never been donebefore—combine a simpler theory with personalobservation, and computation with new tables,to explain a new solar system. Copernicus gaveRheticus permission to tell others about thistheory, and the mathematician wrote aboutCopernicus’s work in his own publication Narratioprima (First Communication), crediting the orig-inator as “The Reverend Father Dr. Nicholas ofTorun, Canon of Ermland.” The Catholics em-braced the work of the good Reverend Father.The Lutherans, however, were another matter.

The Protestant leader Martin Luther (1483–1546) blasted Copernicus for his radical andheretical ideas, quoting the scripture “Joshua

bade the sun and not the earth to stand still,” asproof that Copernicus was doing the devil’swork, and emphatically stating that he believedthe “fool” Copernicus would “reverse the entireArs Astronomiae,” the science of all knownastronomy, if he continued putting forth suchludicrous ideas.

But the persistent Rheticus would not letCopernicus hide his work any longer, and heconvinced Copernicus to let him get the workprinted in Nuremberg. In 1542 Rheticus tookCopernicus’s manuscript to Nuremberg, where itsoon found its way into the publisher’s houseand the hands of a Lutheran priest, AndreasOslander. Not wanting to stir things up with hisfellow Lutherans, Oslander took it upon himselfto write an anonymous preface, making it lookas though Copernicus had written it himself, stat-ing that the hypotheses contained in the bookwere not necessarily true, “nor even probable.”

While many of Copernicus’s ideas wereflawed—for example, his belief, like Ptolemy’s,that all orbits were perfectly circular—they pro-vided the foundation for a major shift in think-ing about the order of the universe. But not inCopernicus’s lifetime. His book, De revolution-ibus orbium coelestium (On the revolutions of theheavenly spheres) was finally published and aprinted copy delivered, reportedly on May 24,1543, to him in Frauenberg. A victim of stroke,he died that same day.

Oslander’s disclaimer served to lead many tobelieve that Copernicus’s theories were incon-sequential to the author himself, although thenewly calculated tables were considered use-ful. As for the Lutherans, the publication an-gered them even more. Seven years later, theLutheran leader Melanchthon (1497–1560) wasstill staunchly denouncing Copernicus, quotingthe Bible, and decreeing that with “these divinetestimonies we will cling to the truth.” Overallacceptance of Copernicus’s theories did not hap-pen. In addition to the religious flak the bookwas taking, the scholars of the time dismissed

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the heliocentric system completely. His bookwas not printed again until 1566, and then notagain until 1617. But the work caught the spiritand minds of a few important figures who notonly perpetuated the theories but also gave themnew legs to stand on.

Giordano Bruno was one brave soul whobelieved in Copernicus’s heliocentric system.But by the time he started to spread the wordabout his beliefs, the Catholic Church had de-creed that the act of declaring the Sun as thecenter of the universe was heresy, and Brunowas burned alive at the stake for speaking histruths.

The biggest shift leading to the acceptanceto Copernicus’s new order happened whenJohannes Kepler learned about the heliocentricsystem as a student at the university in Tubingen.Kepler communicated with Galileo Galilei, whoconfessed that for “many years,” he had agreedwith Copernicus. He told Kepler that he hadeven written arguments for and against the ideas,but had not told anyone about this “until now. . . deterred by the fate of Copernicus himself,our master, who although having won immortalfame with some few, to countless others appears. . . as an object of derision and contumely.” Hetold Kepler that “Truly, I would venture to pub-lish my views if more like you existed; since thisis not so, I will abstain.”

Kepler’s passionate reply called upon Galileoto show his proofs to the world: “Be confidentGalilei and proceed!” It was 1597. An undeni-able change must have been written in the stars.Galileo surely saw it when he made his first tel-escope in 1609. Unfortunately, the CatholicChurch changed its once-favorable stance onCopernicus, and the writings of all three menwere declared heresy.

Centuries later, in 1835, after Galileo’s im-portant work had finally been back in circula-tion for nearly 100 years, the church and thescientific community were finally beginning tocoexist. Acceptance of heliocentric thinking could

freely take place, as the books of Galileo, Kepler,and the man who started it all, Copernicus, wereremoved from the church’s list of forbiddenbooks.

5 Curtis, Heber Doust(1872–1942)AmericanAstronomer

Heber Curtis gained national attention in 1920when he engaged in the “Great Debate” over thesize of the universe with fellow American as-tronomer HARLOW SHAPLEY. Curtis supportedthe daring hypothesis that spiral nebulas wereactually “island universes”—that is, other galax-ies, existing far beyond the Milky Way Galaxy.This radical position meant that the observableuniverse was much larger than anyone daredimagine. By 1924 EDWIN POWELL HUBBLE wasable to support Curtis’s hypothesis, when hedemonstrated that the great spiral Andromeda“nebula” was actually a large galaxy similar to,but well beyond, the Milky Way.

Heber Curtis was born in Muskegon,Michigan, on June 27, 1872. As a child, hewent to school in Detroit. He then studiedthe classic languages (Latin and Greek) at theUniversity of Michigan for five years, receivinghis bachelor of arts degree in 1892 and his mas-ter of arts degree in 1894. Following gradua-tion, Curtis moved to California to accept aposition at Napa College in Latin and Greekstudies. However, while teaching the classics, hebecame interested in astronomy and volun-teered as an amateur observer at the nearby LickObservatory. In 1896 he became a professor ofmathematics and astronomy at the College ofthe Pacific, following a merger of that institu-tion with Napa College.

In 1900 Curtis served as a volunteer mem-ber of the Lick Observatory expedition thattraveled to Thomaston, Georgia, to observe a

Curtis, Heber Doust 93

solar eclipse. His enjoyment of and outstandingperformance during the eclipse expedition con-verted Curtis’s amateur interests in astronomyinto a lifelong profession. After his first solar

eclipse expedition, he entered the Universityof Virginia on a fellowship and graduated in1902 with his doctorate in astronomy. Aftergraduation he joined the staff of the LickObservatory as an astronomer. From 1902 to1909 he made precise radial velocity measure-ments of the brighter stars in support ofWILLIAM WALLACE CAMPBELL’s observationprogram. Starting in 1910, Curtis became in-terested in photographing and analyzing spiralnebulas. He was soon convinced that these in-teresting celestial objects were actually isolatedindependent systems of stars, or “island uni-verses,” as IMMANUEL KANT had called them inthe 18th century.

Many astronomers, including Harlow Shapley,opposed Curtis’s hypothesis about the extra-galactic nature of spiral nebulas. On April 26,1920, Curtis and Shapley engaged in theirfamous “Great Debate” on the scale of the uni-verse and the nature of the Milky Way Galaxyat the National Academy of Sciences, inWashington, D.C. At the time, the vast major-ity of astronomers considered the extent of theMilky Way Galaxy synonymous with the size ofthe universe—that is, they thought the universewas just one big galaxy. However, neither as-tronomer involved in this highly publicized de-bate was completely correct. Curtis argued thatspiral nebulas were other galaxies similar to theMilky Way—a bold hypothesis later proven tobe correct. But he also suggested that the MilkyWay was small and that the Sun was near itscenter—both of these ideas were subsequentlyproven incorrect. Shapley, on the other hand,incorrectly opposed the hypothesis that spiralnebulas were other galaxies. He argued that theMilky Way Galaxy was very large (much largerthan it actually is) and that the Sun was far fromthe galactic center.

In the mid–1920s the great American as-tronomer EDWIN POWELL HUBBLE helped to re-solve one of the main points of controversywhen he used the behavior of Cepheid variable

The American astronomer Heber Curtis stands on aladder at the eyepiece of the 24-inch Crossleyreflector telescope at the Lick Observatory. Curtisgained national attention in 1920 when he engaged inthe “Great Debate” over the size of the universe withfellow American astronomer Harlow Shapley. Curtissupported the then-daring hypothesis that spiralnebulas were actually “island universes”—that is,other galaxies far beyond the boundaries of the MilkyWay Galaxy. (Courtesy AIP Emilio Segrè VisualArchives, Shapley Collection)

94 Curtis, Heber Doust

stars to estimate the distance to the AndromedaGalaxy. Hubble showed that this distance wasmuch greater than the size of the Milky WayGalaxy proposed by Shapley. So, as Curtis hadsuggested, the great spiral nebula in Andromedaand other spiral nebulas could not be part of theMilky Way and must be separate galaxies. In the1930s astronomers proved that Shapley’s com-ments were more accurate concerning the actualsize of the Milky Way and the Sun’s relative lo-cation within it. Therefore, when viewed fromthe perspective of science history, both eminentastronomers had argued their positions usingpartially faulty and fragmentary data. The Curtis-Shapley debate triggered a new wave of astro-nomical inquiry in the 1920s that allowedastronomers like Hubble to determine the truesize of the Milky Way and to recognize that it isbut one of many other galaxies in an incrediblyvast, expanding universe.

In 1920 Curtis became the director of theAllegheny Observatory of the University ofPittsburgh. During the next decade he improvedinstrumentation at the observatory and partici-pated in four astronomical expeditions to ob-serve solar eclipses. In 1930 he returned to theUniversity of Michigan as a professor of as-tronomy and the director of the university’sastronomical observatories. He served in thosepositions until his death in Ann Arbor,Michigan, on January 9, 1942. His wife, MaryD. Rapier Curtis, his daughter, and three sonssurvived him. He was president of theAstronomical Society of the Pacific (1912), afellow of the American Association for theAdvancement of Science (1924), vice presidentof the American Astronomical Society (1926),a member of the American National Academyof Sciences, and foreign associate of the RoyalAstronomical Society in London.

95

D5 Dirac, Paul Adrien Maurice

(1902–1984)BritishPhysicist, Mathematician

Speaking at a dedication of a memorial plaquebeing unveiled at London’s Westminster Abbey,the famous physicist SIR STEPHEN WILLIAM

HAWKING said, “Paul Dirac has done more thananyone this century, with the exception ofALBERT EINSTEIN, to advance physics and changeour picture of the universe.”

Born in Bishopston, Bristol, United Kingdom,to a Geneva-born Swiss-French father CharlesDirac, and a Cornwall-bred mother FlorenceHannah Holton, Dirac, his older brother Reginald,and their younger sister Beatrice endured a harshchildhood under their father’s strict disciplineand generally spent their time in an unhappyhousehold. Both boys would become alien-ated from their father by the time they left forcollege.

Dirac found solace in his studies, and by thetime he graduated from Bishop Primary Schoolhis exceptional talent for mathematics had be-come apparent. In 1914, at age 12, he enteredthe secondary school at Merchant VenturersTechnical College, where his father taughtFrench. Dirac would later comment that asWorld War I broke out, the older students went

off to military service, allowing the youngerstudents better and more frequent access to thescience laboratories and other facilities.

He graduated at the top of his class, and in1918, he went to the University of Bristol tostudy electrical engineering before applyingfor and receiving a scholarship to CambridgeUniversity in 1921. But the scholarship requiredadditional money for full support, which he wasunable to obtain, so he enrolled in BristolUniversity. There, he continued to excel, andgraduated with a B.S. degree in mathematicswith honors in 1923. At this time he earned aresearch grant at St. John’s College at Cambridge.

During this period, classical physicists(Newtonian scholars) were having trouble rec-onciling SIR ISAAC NEWTON’s physics with thebehavior of electrons and atoms, and were la-boring to develop a new theory to explain it. AtCambridge, Dirac studied under Ralph Fowler(1889–1944), the leading theoretician versed inthe new theory of quantum physics, and becameenamored of the algebraic commutators putforth by Werner Heisenberg (1901–76).

Dirac soon developed his own theory, a com-bination of quantum mechanics and special rel-ativity, which included wave mechanics and ma-trix mechanics. By the time Dirac’s doctoralthesis, “Quantum Mechanics,” earned him hisPh.D. in 1926, he already had 11 papers in

96 Dirac, Paul Adrien Maurice

print. The thesis was widely acclaimed and hewas elected a Fellow of St. John’s College in1927.

After receiving his degree, Dirac went toCopenhagen to work with Niels Bohr (1885–1962), then went to Göttingen where he workedwith Robert Oppenheimer (1904–67), MaxBorn (1892–1970), James Franck (1882–1964),and the Russian Nobel laureate Igor Tamm(1895–1971). He made it a point to visit theSoviet Union several times, first in 1928 andthen almost once a year throughout the 1930s.

In 1928 Dirac published his famous “spin-1/2 Dirac Equation,” which is still widely usedtoday, and which explained the mysterious mag-netic and “spin” properties of the electron. Heused this equation to predict the existence of aparticle with the same mass as an electron, butwith an opposite charge (that is, a positivelycharged “antimatter” electron). This antimatterwas subsequently discovered and called apositron in 1932 by CARL DAVID ANDERSON.Today positrons are used every day in medicine,in PET (positron emission tomography) scan-ners that pinpoint places in the brain, such aswhere drugs are chemically active, which worksby detecting the radiation as the positrons emit-ted from radioactive nuclei annihilate ordinaryelectrons nearby.

In 1930 Dirac published his epic ThePrinciples of Quantum Mechanics, which is still inprint, and in 1932 he was appointed LucasianProfessor of Mathematics at Cambridge, a posthe held for 37 years, which was formerly held byNewton and since 1980 by Hawking. Also in1930, he was made a Fellow of the Royal Society,and would be awarded that society’s Royal Medalin 1939 and the prestigious Copley Medal in1952.

The publication of his book took the physicscommunity by storm, transformed the currentimage of the atomic universe, and resulted in hissharing the 1933 Nobel Prize in physics at 31years of age with Austrian Erwin Schrödinger

(1887–1961). A shy and retiring fellow whoabhorred the limelight, Dirac at first wanted torefuse the Nobel Prize because of the publicityit would generate, but changed his mind whenhe was told that refusing it would bring onlymore publicity than ever upon him.

The years 1934 and 1935 were equally dra-matic, for both professional and personal rea-sons. Dirac accepted an invitation to visitPrinceton University to meet the famousHungarian physicist and future Nobel laureate(1963) Eugene Wigner (1902–95). While Diracwas there, Wigner’s sister, Margit, came fromBudapest to visit her brother, and Dirac fell inlove. Married in London, the two eventually hadtwo daughters. Margit had two sons by a previ-ous marriage, and they took Dirac’s name; oneof them, Gabriel Andrew Dirac, became a fa-mous pure mathematician and was a professor ofpure mathematics at the University of Aarhusin Denmark.

During World War II Dirac worked on ura-nium separation and nuclear weapons with aBirmingham group investigating atomic energy,an assignment that led the British governmentto ban him from visiting the Soviet Union un-til 1957.

Dirac shunned all honorary degrees, ofwhich dozens were showered on him, but hereadily accepted honorary admission to re-spected academies and scientific societies. Ofthese there are also dozens, but primary amongthem were the USSR Academy of Sciences in1931; Indian Academy of Science in 1939;Chinese Physical Society in 1943; the RoyalIrish Academy in 1944; the Royal Society ofEdinburgh in 1946; Institut de France in 1946;the National Institute of Sciences of India in1947; the American Physical Society in 1948;the National Academy of Sciences in 1949; theNational Academy of Arts and Sciences in 1950;Accademia delle Scienze di Torino in 1951;Academia das Ciencias de Lisboa in 1953;Pontifical Academy of Sciences, Vatican City,

Doppler, Christian Andreas 97

in 1958; Accademia Nazionale dei Lincei,Rome, in 1960; the Royal Danish Academy in1962; and the Académie des Sciences de Parisin 1963. He was appointed to the Order of Meritin 1973.

After a glorious career reshaping the wayphysicists looked at the inner and outer uni-verses, Dirac retired from Cambridge in 1969and moved his family to Florida. He held visit-ing appointments at the University of Miamiand at Florida State University (FSU). In 1971he was appointed professor of physics at FSU,where he continued his research and continuedto travel as well. In 1973 and 1975 he lectured atthe Physical Engineering Institute in Leningrad.

“One of the most influential scientists ofthe twentieth century,” as the editor of PhysicsWorld called him, this Bristol-born giant of theworld of quantum physics died in Tallahassee in1984.

5 Doppler, Christian Andreas(1803–1853)AustrianMathematician

Anyone who has ever gotten a speeding ticketcan thank Christian Doppler. It was he who de-veloped the famous “Doppler effect,” which isthe principle used in speed guns and traffic radar.

Doppler’s family had been stonemasons inSalzburg, Austria, since 1674, and it was ex-pected that he, too, would enter the family busi-ness. However, he was born to ill health and bythe time he reached his teens he was too frailfor the demanding work of stonemasonry.

After primary school in Salzburg, he at-tended secondary school in nearby Linz, but wasonly an average student. When his parents con-sulted a mathematics professor at the SalzburgLyceum as to young Doppler’s potential, the pro-fessor suggested that he might have a talent inmathematics, and recommended that Doppler

enter the Vienna Polytechnic Institute. Dopplerenrolled in 1822.

Doppler finally began to excel and, indeed,mathematics turned out to be his forte. Aftergraduating in 1825, he returned to Salzburg andstudied philosophy at the Lyceum, then returnedto Vienna, this time to study astronomy, me-chanics, and higher mathematics at the univer-sity. In 1829 Doppler began a four-year tenureas an assistant to a professor of higher mathe-matics and mechanics. He published his firsttechnical paper, “A Contribution to the Theoryof Parallels,” plus three others over the four-yearperiod.

By the time Doppler was 30 years old, hehad grown weary of being someone’s assistant,and he began to think in terms of finding a per-manent position in his own right. However, itwas not easy at this time in Austria. Applicantsfor vacant professorships had to enter a publiccompetition for the available jobs, in which theapplicant had to take a day-long written examand then give a lecture to an appointed panel ofexaminers. Politics played a key role in gettingthe final appointment.

Doppler applied for professorships at severalschools in this manner, including the universi-ties in Gorizia, Linz, Ljubljana, Salzburg, theTechnical Secondary School in Prague, andVienna Polytechnic Institute. Meanwhile, toearn a living he took a job as a bookkeeper at acotton spinning factory. Through all thesestressful efforts, his health, which was not goodto begin with, began to deteriorate.

The public competition for all those jobstook almost two years to complete. At one pointDoppler gave up and decided to move toAmerica, but just when he was interviewing theAmerican consul in Munich, he received thehappy news in 1835 that he had won the job atthe Technical Secondary School in Prague.

Once again, Doppler was unhappy with thesituation. He considered teaching elementarymathematics in secondary school to be beneath

98 Doppler, Christian Andreas

him, which indeed it was, and he cast aroundfor a better job. He failed again at getting a po-sition at the Polytechnic Institute, but in 1836,he got a part-time job teaching higher mathe-matics four hours a week, and kept this job fortwo years.

In 1837 politics reared its ugly head again.The post of professor of geometry and mathe-matics at the Polytechnic became vacant, andDoppler filled the post. However, even as he wasdischarging his duties, the institute held a pub-lic competition for his job behind his back.When he found out about it, he expressed hisdismay in strong terms, and was told he did nothave to take part in the competition. It remainsa mystery why it was even held at all, becauseDoppler was finally appointed formally to theposition of full professorship in 1841.

It was during this time that Doppler pre-sented his magnum opus, a paper entitled “Onthe Colored Light of the Double Stars andCertain Other Stars of the Heavens,” which ex-plained Doppler’s idea that sound was composedof longitudinal waves that could be compressedor expanded, and that the frequency of the wavevaried according to its velocity in relation to anobserver.

As a practical proof of his theory, Dopplerarranged for a trumpeter to sound a series of thesame notes over and over as he rode on a flatcar pulled by a speeding railroad train. On theground he stationed another musician with theability to identify musical tones by ear. As thetrain approached closer and then rushed past andmoved quickly away, the second musicianrecorded that the notes from the trumpetersounded different when the train was ap-proaching than when it was moving away. Thuswas born the famous “Doppler effect,” whicheveryone has experienced when riding a swiftlymoving vehicle past a ringing bell.

Doppler also tried to prove that his theoryapplied to light, but was unable to and it was leftfor Armand Fizeau (1819–96) to generalize and

then prove Doppler’s work as it applies to light.Doppler’s work placed him in the pantheon ofastronomy because it was the first major contri-bution to the discovery that the universe isexpanding.

Even with his new fame, he was having ahard time of it at work. When students com-plained that his examinations were too difficult,he was reprimanded by the authorities and thestress further affected his health. At about thistime he was also under great duress to partici-pate in the examination of hundreds of studentsapplying for competitive positions. For example,one report states that in January and February1843, he had to examine 256 students in 17 days,including six hours of both oral and writtenexams in arithmetic and algebra. The same num-ber of students sat for theoretical geometry ex-ams in June and July, and in August Doppler hadto examine 145 students in eight days. The strainwas too much for him, and in 1844 he finally re-quested a sick leave, which lasted two years be-fore he was well enough to return to work.

In 1846 Doppler changed venues, acceptinga professorship of mathematics, physics, and me-chanics at the Academy of Mines and Forests inBanska Stiavnica, mostly to escape the politicalunrest as the monarchy began to topple inPrague. By now he was becoming famous becauseof his widely celebrated Doppler effect thesis,and was appointed professor again at thePolytechnic Institute. In 1848 Doppler waselected to the Imperial Academy of Sciences inVienna and received an honorary doctorate fromthe University of Prague. In 1850 he was ap-pointed the first director of the newly establishedInstitute of Physics at Vienna University.

But his health took a serious turn for theworse and by 1852 he decided to move to Venicefor the warmer climate. He could not recover,though, and he died there in March 1853.

Although Doppler also published significantpapers on electricity and magnetism, describedthe variation of magnetic declination with time,

Douglass, Andrew Ellicott 99

and published papers on optics and astronomy,his definition of the Doppler effect was hiscrowning glory. Today the Doppler effect is theprinciple behind technologies used across thespectrum of industry. In medicine, Doppler ul-trasound is used widely in imaging instrumenta-tion and vascular studies. Doppler radar is bothan important military tool and useful in weatherforecasting. Oceanographers use Doppler sonarto map ocean currents. Law enforcement usesspeed guns and traffic radar. And in astronomy,his principle is still useful for measuring thespeed of bodies and searching for new planets.

5 Douglass, Andrew Ellicott(1867–1962)AmericanAstronomer, Environmental Scientist

Early in the 20th century, the American as-tronomer Andrew Douglass postulated thatthere might be a measurable relationship be-tween sunspot activity and the terrestrial cli-mate. To explore this hypothesis, he started thefield of dendrochronology (tree-ring dating).Despite his years of investigation, he could onlylink tree ring data with local climate episodes,since this data could not provide an unambigu-ous link between past global climate conditionsand sunspot activity. However, his pioneering ef-forts provided both archaeologists and climatol-ogists with an important new research tool andalso anticipated the efforts by modern scientistswho employ sophisticated satellites in their con-temporary investigation of Sun-Earth environ-mental relationships.

Douglass was born in Windsor, Vermont, onJuly 5, 1867. He came from a family with a longtradition of academic service; his father andgrandfather were both college presidents. Hegraduated with honors from Trinity College inHartford, Connecticut, in 1889, and upon grad-uation accepted a research assistantship at the

Harvard College Observatory. From 1891 to1893 Douglass served as the chief assistant onthe astronomical expedition that founded theHarvard Southern Hemisphere Observatory inArequipa, Peru.

When Douglass returned from Peru, PERCIVAL

LOWELL hired him to help locate the most suit-able site in the “Arizona Territory” (statehooddid not occur until 1912) for a new astronomi-cal observatory dedicated primarily to supportLowell’s obsession with Mars. Douglass recom-mended the city of Flagstaff and moved there af-ter the founding of the Lowell Observatory in1894. He was a good astronomer and soon be-came Lowell’s chief assistant. Douglass had theprimary task of collecting data about Mars, butthe young astronomer from Vermont soon fellinto sharp disagreement with Lowell on howcertain data were being selectively applied tosupport Lowell’s rather unscientific approach toprove Mars was inhabited by intelligent beings.Lowell was actually a skilled observational as-tronomer, but his results were often blurred bythe preconceived notion that GIOVANNI VIRGINIO

SCHIAPARELLI’s canali (channels) were canalsbuilt by a race of intelligent beings. Afternumerous “scientific method” clashes, Lowellwanted no more internal dissidence, and he firedDouglass in 1901.

Unperturbed, Douglass remained in theFlagstaff area until 1906, when he joined theUniversity of Arizona in Tucson as its first pro-fessor of astronomy. He also taught physics atthe university and became the first astronomerto photograph the zodiacal light. In 1916 hesecured funding from the Steward family to con-struct an astronomical observatory at the uni-versity. Two years later Douglass began his longand productive tenure as the director of the newSteward Observatory. Construction of the ob-servatory was completed in 1923 and the newfacility represented the first of several importantmilestones that would make the University ofArizona an internationally recognized center of

100 Douglass, Andrew Ellicott

astronomy. As the city of Tucson grew withstatehood, Douglass found it necessary to movethe observatory to Kitt Peak (south of the city)to avoid the problems of light pollution from theexpanding urban environment. Douglass servedas the director of the Steward Observatory un-til 1937, when he became the director of theuniversity’s Laboratory for Tree-Ring Research.Although a skilled astronomer, Douglass is nowbest remembered for his pioneering work in tree-ring dating.

While working in Flagstaff, Douglass hadthe great inspiration that led him to create thefield of dendrochronology (tree-ring dating). Atthe time, he was searching for a measurable en-vironmental relationship that would link thesunspot cycle and past climate episodes. He rea-soned that vegetation changes, especially as por-trayed by the growth of certain species of treessuch as ponderosa pines, Douglas firs, and thegreat sequoias (giant redwoods), might providethe solution. Douglass hypothesized that the mo-tion of the planets and the behavior of the Sunwere responsible for weather and climatechanges. Working in Arizona and portions ofNew Mexico, Douglass was soon able to analyzethe rings of local trees, primarily pines andDouglas firs, and relate the size of each ring toprevious annual levels of rainfall. A tree pro-duces a ring each year and, depending on cli-mate conditions, certain species of trees producewide rings during wet years and narrow rings dur-ing dry years. In effect, the cross-sections of thesetrees recorded past rainfall and served as a nat-ural clock.

Recognizing that tree-ring data in Arizonarepresented a record of past rainfall, Douglassfurther hypothesized that the tree-ring datamight also represent a quantitative indicationabout the abundance of solar energy and the in-fluence of the Sun on Earth’s past climate. By1911 he began studying the rings of the great se-quoias, trees that are estimated to be between1,800 and 2,700 years old. Between 1919 and

1936 he summarized his pioneering efforts in histhree-volume treatise entitled Climate Cycles andTree Growth. While his tree-ring data fromArizona and New Mexico indicated past periodsof drought, to his disappointment these datagenerally did not correlate with similar climateepisodes in other parts of the world. He andother scientists could only conclude that the pastclimate changes revealed by such tree-ring“clocks” were most likely only local environ-mental episodes, and not necessarily correlatedwith sunspot activity and climate stress on aplanetary scale. Contemporary Earth system sci-ence models, using sophisticated spacecraft andcomputers, now help scientists investigate link-ages between the Sun’s long-term behavior andterrestrial weather and climate trends.

While never able to personally prove hisoriginal hypothesis and link sunspot activitywith vegetation changes and terrestrial climate,Douglass established tree-ring dating as a valu-able tool for archaeologists who needed to ac-curately date ancient structures and for envi-ronmental scientists who were searching fordefinitive records of past climate episodes. As ahistoric note, the American chemist WillardLibby (1908–80) invented radiocarbon dating in1949. Libby’s carbon-14 radioisotope techniqueprovided archaeologists a universal clock withwhich to study the past. Nevertheless, den-drochronology still remains a useful tool in ar-chaeology and environmental studies and oftenprovides a useful calibration tool for the radio-carbon technique.

After an additional two decades of serviceto the University of Arizona, Douglass retiredfrom his position as director of the Laboratoryof Tree-Ring Research in 1958. He died inTucson on March 20, 1962. The world-famousSteward Observatory and the field of den-drochronology are two important legacies of thisremarkable scientist. His accomplishmentsearned him an appointment as research associ-ate to the Carnegie Institution of Washington

Drake, Frank Donald 101

and a life membership to the National GeographicSociety.

5 Drake, Frank Donald(1930– )AmericanRadio Astronomer

Frank Drake was born in 1930 to Richard andWinifred Drake and raised on Chicago’s SouthShore with his sister, Alma, and brother, Robert.Like millions of others of his generation, hespent hundreds of hours experimenting withmotors, clocks, chemistry sets, radios, and gaz-ing up at the stars on clear summer nights. Alsolike millions of kids who became hooked onscience fiction, young Drake began to wonderabout the existence of life elsewhere in theuniverse.

Drake won a Reserve Officers’ Training Corps(ROTC) scholarship to Cornell University, ma-jored in electronics, became fascinated by as-tronomy, and in 1952 received a B.A. degree inengineering physics. However, in his junior yearhe attended a lecture by the famous astrophysi-cist Otto Struve (1897–1963), during whichStruve presented accumulating evidence thatmany stars in the Milky Way Galaxy had plan-etary systems around them. Further, Struve wenton to speculate that with such a vast number ofsolar systems, the chances were good that one ofthem could sustain life. At last, Drake had foundsomeone else who agreed with his growing con-tention that the odds were almost overwhelm-ing that life did exist somewhere else.

Drake then spent three years in the U.S.Navy as an electronics officer on the U.S.S.Albany, accumulating experience in fixing andoperating the most modern high-tech electronicequipment then available. When he finally leftthe navy, Drake decided to go to Harvard andstudy optical astronomy, but as fate would have itthe only course available was in radio astronomy.

This turned out to be a perfect fit with his navyexperience.

Now hooked on radio astronomy, Drake re-ceived his Ph.D. in astronomy from Harvard in1958. He then took a position at the newlyfounded National Radio Astronomy Observatory(NRAO) in Green Bank, West Virginia, wherehe eventually became head of the TelescopeOperations and Scientific Services Division.There Drake organized a formal search for ex-traterrestrial signals called Project Ozma, a two-month observation of the close stars Tau Cetiand Epsilon Eridani, using the 85-foot singlechannel antenna tuned to the 1420 megahertzfrequency of hydrogen. No signals were detected.

In 1959 two physicists at Cornell, GiuseppiCocconi and Philip Morrison, published a paperin which they described the possibility of usinga microwave radio for interstellar communica-tion, a potential apparatus that Drake had alsobeen contemplating.

In 1961 Drake and J. Peter Pearman, of theSpace Science Board of the National Academyof Sciences, organized the now famous Searchfor Extra-Terrestrial Intelligence (SETI) con-ference at the NRAO. It was a small meeting,with a dozen or so scientists attending to sharetheir views and interest in searching for extra-terrestrial life. In preparation for this meeting,Drake formulated what became known as theDrake equation to estimate the number of pos-sible technologically advanced civilizationsthat could be sending radio signals in Earth’sdirection:

N 5 N*fpneflfifcL

in which

N* represents the number of stars in the MilkyWay Galaxy, about 200 billion;

fp is the fraction of stars that have planets aroundthem; thanks to the Hubble telescope newplanets are being discovered every month, butDrake estimates this to be 20 percent;

102 Draper, Henry

ne is the number of planets per star that are capa-ble of sustaining life; based on this solar system,the quantity is given as 4—Earth, Venus, Mars,and possibly one of Jupiter’s moons;

fl is the fraction of planets in ne where lifeevolves; current estimates range from 100percent to close to 1 percent, so 50 percentis used as a good arbitrary figure;

fi is the fraction of fl where intelligent lifeevolves; again, guesses range from 100 per-cent to 1 percent, the logic being that intelli-gence is such a survival advantage that it willcertainly evolve;

fc is the fraction of fi that communicate; againimpossible to guess, but experts give it 10percent to 20 percent;

L is the length of time the communicating civ-ilizations send detectable communicationsinto space.

Using us as an example, the expected life-time of the Sun and Earth as roughly 10 billionyears, and thus far humans have been commu-nicating with radio waves for less than 100 years.The figure for this variable depends solely on es-timates of how long the Earth’s civilization willsurvive.

All of these variables multiplied togetherresults in N, the number of communicatingcivilizations in the galaxy.

After a brief tour with the Jet PropulsionLaboratory in Pasadena, California, in 1963,Drake joined the Center for Radiophysics andSpace Research at Cornell, and in 1965 becamedirector of Cornell’s Arecibo Observatory inPuerto Rico. He returned to Cornell in 1968 aschairman of the astronomy department, and wasGoldwin Smith Professor of Astronomy until1984. He then joined the faculty of the Universityof California at Santa Cruz (UCSC) as dean ofthe natural sciences division, then professor of as-tronomy and astrophysics. He continues histenure at UCSC today and is still chairman of theBoard of Trustees of the SETI Institute.

Besides sharing in the discovery of the radi-ation belts of Jupiter, conducting the first SETIorganized searches, and positing Drake’s equa-tion, Drake’s methods were used in sending ad-ditional messages to outer space on the Pioneer10 and Pioneer 11 (with plaques designed byDrake, CARL SAGAN, and Linda Sagan), and onboard the Voyager spacecraft, conceived byDrake and compiled by several scientists.

Drake has received numerous honorary de-grees and appointments, was chairman of theNational Research Council Board of Physics andAstronomy, a member of three NAS/NRCAstronomy Survey committees, and president ofthe Astronomical Society of the Pacific. TheFrank D. Drake Planetarium was dedicated inNorwood, Ohio, in 1983. He has also writtenmore than 150 articles, and the book Is AnyoneOut There? (1992), an autobiographical workcoauthored with Dava Sobel.

Readers who wish to play with Drake’s equa-tion may enter their own variable values on theInternet at http://www.planetarysystems.org/drake_equation.html. Drake’s own solution to hisequation is N=10,000 communicative civiliza-tions in the Milky Way Galaxy.

5 Draper, Henry(1837–1882)AmericanAstronomer, Photographer

Henry Draper took the first photograph of a dis-tant astronomical object, the Orion Nebula, giv-ing a push to celestial photography that openedmodern astronomy to a new vision of the uni-verse. All the men in the Draper family madepioneering strides in science, especially in thefields of meteorology and astronomy in the 19thcentury. Draper’s father, John William Draper,who was primarily a chemist, took the first pho-tograph, a daguerreotype, of the Moon in 1839,one of the first human photographs in 1840, and

Draper, Henry 103

the first photograph of the diffraction spec-trum. Henry’s brother John was a noted physi-cian and chemist, and his brother Daniel wasa meteorologist who established the New YorkMeteorological Observatory in Central Park in1868.

Draper was born in Virginia to JohnWilliam Draper and Antonia Coetana de PaivaPereira Gardner Draper, whose father was thepersonal physician to the emperor of Brazil. Asa boy, Draper assisted his father in pursuingphotographic techniques, and at age 13 helpedhim take pictures of microscope slides for atextbook. When he graduated from medicalschool in 1857, he used this experience towrite his thesis on the spleen using photo-graphs of microscope slides as illustrations.However, the law at the time dictated that hecould not receive his medical degree until hewas 21, so he took a year off and traveledthrough Europe.

During his travels, Draper visited LordRosse’s observatory in Ireland, which at the timeutilized the world’s largest telescope, the 72-inchLeviathan reflector. The experience kindledwithin him an urgent desire to investigate theuse of photography in astronomical observationswhen he returned home. To this goal, he builthis own observatory on his father’s estate atHastings-on-Hudson, New York, while he wasbeginning his medical career. Draper joined thestaff at Bellevue Hospital in New York City, andlater became first a professor and then dean ofthe New York University School of Medicine.

In 1867 Draper married Anna Mary Palmer,a wealthy socialite who not only became an ami-able and capable hostess, frequently entertain-ing the prominent scientists and celebrities ofthe day, but who also became a proficient anddedicated laboratory assistant to Draper.

Draper is best known for recording on pho-tographic plates the Great Nebula of Orion onSeptember 30, 1880. The images were not of thebest quality, but the techniques were improved

upon rapidly after his death in England. Drapertook the first stellar spectrum photograph ofVega in August 1872, and, with Tebbutt’s cometin 1881, made the first wide-angle photographof a comet’s tail and the first spectrum of acomet’s head. Refining his father’s work to a sig-nificant degree, he produced a great number ofphotographs of the Moon and made a bench-mark spectrum of the Sun in 1873. He also tookspectra of the Orion Nebula, the Moon, Mars,Venus, and several first magnitude stars.

From there Draper went on to invent theslit spectrograph, advancing the state-of-the-art in telescope clock drives and instrument op-tics. He also wrote a chemistry textbook andpublished many papers on his astronomicalwork and telescope design. He was one of thefirst to recommend building an observatory inthe Andes Mountains to avoid atmosphericpollution.

Before his sudden death on November 20,1882, of double pleurisy during a hunting trip tothe Rocky Mountains, he had received honorarylaw degrees from New York University and theUniversity of Wisconsin, a congressional medalfor directing a U.S. expedition to photographthe transit of Venus in 1874, and was electedboth to the National Academy of Sciences andGermany’s Astronomische Gesellschaft. He wasa member of the American PhotographicSociety, the American Philosophical Society,the American Academy of Arts and Sciences,and the American Association for the Advance-ment of Science.

After his death, Draper’s wife established theHenry Draper Memorial Fund to support theadvancement of photography in astronomicalefforts. This fund supported a massive photo-graphic stellar spectrum survey performed byANNIE JUMP CANNON and other women atPickering’s observatory at Harvard University,which became the celebrated Henry DraperCatalogue, or the HD Catalogue, as it is stillknown and used today.

104 Dyson, Sir Frank Watson

5 Dyson, Sir Frank Watson(1868–1939)BritishAstronomer

Sir Frank Watson Dyson participated with SIR

ARTHUR STANLEY EDDINGTON during the May1919 solar eclipse expedition that measured thedeflection of a beam of starlight as it passedclose to the Sun. This effort provided the firstexperimental evidence in support of ALBERT

EINSTEIN’s theory of general relativity. A spe-cialist in solar eclipses and in stellar motion stud-ies, Dyson also served as Astronomer Royal ofScotland from 1905 to 1910 and then asEngland’s Astronomer Royal from 1910 to 1933.

Dyson was born at Measham, near Ashby-de-la-Zouch, Leicestershire, England, on January8, 1868. He was the son of a minister and wonscholarships for his secondary and college edu-cation. Dyson graduated from Trinity College atCambridge University in 1889 with a degree inmathematics. Following graduation, he becamea Fellow at Trinity College in 1891 and thenchief assistant to the Astronomer Royal at theRoyal Greenwich Observatory in 1894. His pri-mary astronomical studies involved the propermotions of stars and participating in solar eclipseexpeditions on which he made special observa-tions of the Sun’s outer regions.

Dyson managed the Carte du Ciel project ofphotographing the entire sky—a project that in-volved an investigation of the proper motion ofmany stars and eventually led other astronomersto discover that the Milky Way Galaxy was ro-tating. In astronomy, the proper motion of a staris its apparent annual angular motion on the ce-lestial sphere—a tiny effect that after thousandsof years causes groups of stars with differences inthe direction of their proper motions to changeshape in some appreciable manner. In collabo-ration with William G. Thackeray, Dyson meas-ured the position of 4,000 circumpolar stars andthen compared these measurements with early

19th-century observations to determine propermotions. Dyson’s efforts helped extend the “starstreaming” work of JACOBUS CORNELIUS KAPTEYN

to fainter stars. In 1904 Kapteyn first noticedthat instead of an anticipated random distribu-tion, the proper motions of stars in the Sun’sneighborhood actually seemed to favor two op-posite directions, called star streams. This wasactually the earliest observational evidence thatthe galaxy was rotating, but astronomers did notimmediately recognize the phenomenon.

Dyson enjoyed participating in solar eclipseexpeditions. At the start of the 20th century, hewas a member of eclipse expeditions to Portugalin 1900, to Sumatra in 1901, and to Tunisia,North Africa, in 1905. These activities made hima recognized expert on the Sun’s corona and chro-mosphere. In 1901 he was elected as a fellow ofthe Royal Society, and he was knighted in 1915.

Dyson is best remembered for organizing andcoordinating the two most significant solareclipse expeditions in 1919, when he sent ex-peditions to the island of Principe, in the Gulfof Guinea off the coast of West Africa, and toSobral in Brazil to carefully measure the posi-tions of stars near the Sun’s rim during theeclipse. Any deflection of starlight would pro-vide evidence to support Einstein’s general the-ory of relativity. While Dyson led the Britishexpedition to Sobral, Brazil, Eddington led theBritish expedition to Principe. It was on Principeduring the solar eclipse of May 29, 1919, thatEddington successfully measured the tiny de-flection of a beam of starlight as the star’s lightjust grazed the rim of the Sun—a subtle, gravi-tationally induced bending that provided scien-tists with their first experimental verification ofgeneral relativity. Dyson also participated onsolar eclipse expeditions to Australia (1922),Sumatra (1926), and Malaya (1929).

Except for his five years in Edinburgh asScotland’s Astronomer Royal from 1905 to 1910,Dyson spent his entire career as an astronomerat the Royal Greenwich Observatory in southeast

Dyson, Sir Frank Watson 105

London. In 1910 he was appointed as England’sninth Astronomer Royal and served in this pres-tigious position until his retirement in 1933. Hemade improvements in precision timekeeping atthe observatory and was instrumental in the firstradio (“wireless”) signal broadcast of time in1924. Upon retirement he and his wife, LadyDyson, focused their attention on the welfare oftheir community. While on a voyage fromAustralia to the United Kingdom Dyson died atsea on May 25, 1939.

His numerous contributions to astronomywere honored in many ways. Dyson received theBruce Gold Medal from the AstronomicalSociety of the Pacific in 1922 and the RoyalAstronomical Society bestowed its Gold Medalon him in 1925. He became a Knight of theBritish Empire (KBE) in 1926. Dyson publishedhis important book, Eclipses of the Sun andMoon, in 1937 in collaboration with the Britishastronomer Sir Richard van der Riet Woolley(1906–86).

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E5 Eddington, Sir Arthur Stanley

(1882–1944)EnglishAstrophysicist

Arthur Eddington was born in Kendall, England,to strict Quaker parents, but his father died whenhe was two years old and he was raised inSomerset by his mother. When he was 16,Eddington was awarded a local scholarship andattended Owens College (now the University ofManchester) where he studied physics andmathematics. After graduating in 1902 he wasawarded a scholarship to study at Cambridge,from which he graduated in 1905, and then wonanother scholarship to study at Trinity College,where his research work won him the covetedSmith Prize, an honor still awarded to graduateresearch students devoted to mathematics, ap-plied mathematics, and theoretical physics. From1906 to 1913 he was chief assistant director of theRoyal Observatory in Greenwich, and in 1914 hewas named Plumian Professor of Astronomy andbecame director of the observatory.

As a Quaker, his conscientious objectorstatus kept him out of World War I and therebyallowed him to continue his studies at Cambridgefrom 1914 to 1918. ALBERT EINSTEIN had pub-lished his theory in 1915, which created a world-wide stir among astrophysicists, claiming that in

a space-time continuum, light is composed ofmatter that will be affected by strong gravita-tional forces. Eddington grasped the significanceof the theory, and when fellow astronomer SIR

FRANK WATSON DYSON pointed out that an up-coming total solar eclipse would be an ideal phe-nomenon to test the theory, Eddington seizedthe opportunity. In 1919 he led an expeditionto Brazil to observe a total eclipse of the Sun,and confirmed with photographic evidence thepredictions of relativity that light rays are indeedbent when they pass stellar objects of great grav-itational fields. Eddington thus became the firstperson to prove Einstein’s theory to be correct,and he confirmed it again on another solareclipse expedition to Príncipe Island in WestAfrica.

During this period at Cambridge he becamerecognized throughout the scientific communityas the world’s foremost authority on the theoryof relativity aside from Einstein himself. In fact,Einstein called Eddington’s Mathematical Theoryof Relativity, published in 1923, “the finest pres-entation of the subject in any language.”

Eddington went on to study the internalcomposition of stars. Among his discoveries wasthat a star’s interior is under radiative equilib-rium, involving the three forces of gravity, gaspressure, and radiation pressure. He demonstratedthat energy could be transported by radiation as

Ehricke, Krafft Arnold 107

well as convection, and that the temperature ofthe center of a star is in the millions of degrees.He also put forth the theory that the chief sourceof star energy was subatomic, supplied mostly byhydrogen that was fused into helium. Most ofthis research was published in his 1926 book,The Internal Constitution of Stars.

In his later years Eddington came to believethat the basic constants of nature, such as themass of the proton and the charge of the elec-tron, were not coincidental but, as he put it, werepart of a “natural and complete specification forconstructing a Universe.” He did not live tocomplete this thesis, but his book on the sub-ject, Fundamental Theory, was published after hisdeath.

Eddington spent most of his life reviewingand critiquing the works of his contemporaries,an endeavor that often leads to controversy andhurt feelings. Eddington’s most famous battle waswith SUBRAHMANYAN CHANDRASEKHAR, thecelebrated Indian American astrophysicist whowas an expert on white dwarfs, stars that haveburned off their internal supply of hydrogen andhave collapsed into themselves as intensely hotbut very small stars. Chandra, as he was called,had postulated that there was an upper limit tothe mass of a white dwarf, a concept thatEddington dismissed as impossible. Because Ed-dington was the most respected astrophysicist ofhis day, Chandra was crushed by the rejection,appealing to several leading physicists of thetime, and it was eventually accepted thatChandra was right and Eddington wrong. Theupper limit of 1.4 solar masses for white dwarfsis today known as Chandrasekhar’s Limit.

This academic defeat notwithstanding,Eddington went on to establish himself as themost prominent and important astrophysicist ofthe interwar years, making several valuablecontributions to the field of physics. During hisrespected career, Eddington was elected a fellowof the Royal Society in 1914, was president of theRoyal Astronomical Society from 1921 to 1923,

was awarded the Bruce Medal in 1924, receivedthe Royal Society Royal Medal in 1928, wasknighted in 1930, and then was president of thePhysical Society from 1930 to 1932. Eddingtondied in Cambridge on November 22, 1944, andhas been remembered as “the father of modernastrophysics.” A crater on the Moon bears thename Eddington in his honor.

5 Ehricke, Krafft Arnold(1917–1984)German/AmericanRocket Engineer

This talented rocket engineer conceived ad-vanced propulsion systems for use in the U.S.space program of the late 1950s and 1960s. Oneof Krafft Ehricke’s most important technicalachievements was the design and developmentof the Centaur upper-stage rocket vehicle—thefirst American rocket vehicle to use liquidhydrogen (LH2) as its propellant. His Centaurvehicle made possible many important militaryand civilian space missions. As an inspirationalspace visionary, Ehricke’s writings and lectureseloquently expounded upon the positive conse-quences of space technology. He anchored hisfar-reaching concept of an “extraterrestrial imper-ative” with the concept of a permanent humansettlement of the Moon.

Ehricke was born in Berlin, Germany, onMarch 24, 1917, at a turbulent time when im-perial Germany was locked in a devastating warwith much of Europe and the United States. Hegrew up in the political and economic chaos ofGermany’s postwar Weimar Republic. Yet, de-spite the gloomy environment of a defeatedGermany, Ehricke developed his lifelong posi-tive vision that space technology would serve asthe key to improving the human condition.

Following World War I, his parents, bothdentists, attempted to find schooling of sufficientquality to challenge him. Unfortunately, Ehricke’s

108 Ehricke, Krafft Arnold

frequent intellectual sparring contests with rigidPrussian schoolmasters earned him widely vary-ing grades. By chance, at age 12, Ehricke sawFritz Lang’s 1929 motion picture, Die Frau imMond (The woman in the moon). The Austrianfilmmaker had hired the German rocket expertsHERMANN JULIUS OBERTH and Willy Ley (1906–69)as technical advisers during the production ofthis film. Oberth and Ley gave the film an ex-ceptionally prophetic two-stage rocket designthat startled and delighted audiences with its im-pressive blast-off. Advanced in mathematics andphysics for his age, he appreciated the great tech-nical detail that Oberth had provided to makethe film realistic, and he viewed Lang’s film atleast a dozen times. This motion picture servedas Ehricke’s introduction to the world of rocketsand space travel, and he knew immediately whathe wanted to do for the rest of his life. He soondiscovered KONSTANTIN EDUARDOVICH

TSIOLKOVSKY’s theoretical concept of a very ef-ficient chemical rocket that used hydrogen andoxygen as its liquid propellants. Then, as ateenager, he attempted to tackle Oberth’s famous1929 book Roads to Space Travel, but struggledwith some of the more advanced mathematics.

In the early 1930s he was still too young toparticipate in the German Society for SpaceTravel (Verein für Raumschiffahrt, or VFR), sohe experimented in a self-constructed laboratoryat home. As Adolf Hitler (1889–1945) rose topower in 1933, Ehricke, like thousands of otheryoung Germans, got swept up in the Nazi youthmovement. His free-spirited thinking, however,soon earned him an unenviable position as aconscripted laborer for the Third Reich. Then,just before the outbreak of World War II, he wasreleased from the labor draft so he could attendthe Technical University of Berlin. There, hemajored in aeronautics, the closest academicdiscipline to space technology. One of his pro-fessors was Hans Wilhelm Geiger (1882–1945),the noted German nuclear physicist. Geiger’s lec-tures introduced Ehricke to the world of nuclear

energy. Impressed, Ehricke would later recom-mend the use of nuclear power and propulsionin many of the space development scenarios hepresented in the 1960s and 1970s.

Wartime conditions played havoc withEhricke’s attempt to earn his degree. While en-rolled at the Technical University of Berlin, hewas drafted for immediate service in the Germanarmy and sent to the western front. Wounded,he came back to Berlin to recover and resumehis studies and in 1942 obtained a degree in aero-nautical engineering from the university. Butwhile taking postgraduate courses in orbital me-chanics and nuclear physics, he was againdrafted into the German army, promoted to therank of lieutenant, and ordered to serve with aPanzer (tank) division on the eastern (Russian)front. But fortune played a hand, and in June1942 the young engineer received new orders,this time reassigning him to rocket developmentwork at Peenemünde. From 1942 to 1945 heworked on the German army’s rocket programunder the overall direction of WERNHER MAGNUS

VON BRAUN.As a young engineer, Ehricke found himself

surrounded by many other skilled engineers andtechnicians whose goal was to produce theworld’s first modern liquid-propellant ballisticmissile, the A-4 rocket. This rocket is betterknown as Hitler’s Vengeance Weapon Two, orsimply the V-2. After World War II the GermanV-2 rocket became the ancestor to many of thelarger missiles developed by both the UnitedStates and the Soviet Union during the coldwar, a period ranging roughly from 1946 to1989.

Near the end of World War II, Ehrickejoined the majority of the German rocket sci-entists at Peenemünde and fled to Bavaria toescape the advancing Soviet army. Swept up inOperation Paperclip along with other keyGerman rocket personnel, Ehricke delayed ac-cepting a contract to work on rockets in theUnited States by almost a year. He did this in

Ehricke, Krafft Arnold 109

order to locate his wife, Ingebord, who was thensomewhere in war-torn Berlin. After a longsearch that culminated in a happy reunion,Ehricke, his wife, and their first child journeyedto the United States in December 1946 to begina new life.

For the next five years, Ehricke supportedthe growing U.S. Army rocket program atWhite Sands, New Mexico, and Huntsville,Alabama. In the early 1950s he left his positionwith the U.S. Army and joined the newly formedAstronautics Division of General Dynamics (for-merly called Convair). There he worked as arocket concept and design specialist and partic-ipated in the development of the first U.S. in-tercontinental ballistic missile, the Atlas. Hebecame a U.S. citizen in 1955.

Ehricke strongly advocated the use of liquidhydrogen as a rocket propellant. While at GeneralDynamics, he recommended the development ofa liquid hydrogen/liquid oxygen propellant up-per-stage rocket vehicle. His recommendationbecame the versatile and powerful Centaurupper-stage vehicle. In 1965 he completed hiswork at General Dynamics as the director of theCentaur program and joined the advancedstudies group at North American Aviation inAnaheim, California. From 1965 to 1968 thisnew position allowed him to explore pathwaysof space technology development across a widespectrum of military, scientific, and industrialapplications. The excitement of examining pos-sible space technologies and their impact on thehuman race remained with him for the rest ofhis life.

From 1968 to 1973 Ehricke worked as a sen-ior scientist in the North American RockwellSpace Systems Division in Downey, California.In this capacity, he fully developed his far-ranging concepts concerning the use of spacetechnology for the benefit of humankind. Afterdeparting Rockwell, he continued his visionaryspace advocacy efforts through his own consult-ing company, Space Global, located in La Jolla,

California. As the U.S. government wounddown Project Apollo in the early 1970s, Ehrickecontinued to champion the use of the Moon andits resources. His extraterrestrial imperative wasbased upon the creation of a selenospheric(Moon-centered) human civilization in space.Until his death in late 1984, he spoke and wrotetirelessly about how space technology providesthe human race with the ability to create anunbounded “open world civilization.”

Ehricke was a dedicated space visionary whonot only designed advanced rocket systems (suchas the Atlas-Centaur configuration) that greatlysupported the first “golden age” of space explo-ration, but also addressed the important, but fre-quently ignored, social and cultural impacts ofspace technology. He created original art to com-municate many of his ideas. He coined the termandrosphere to describe the synthesis of the ter-restrial and extraterrestrial environments. Theandrosphere relates to human integration ofEarth’s biosphere—the portion of Earth thatcontains all the major terrestrial environmentalregimes, such as the atmosphere, the hydros-phere, and the cryosphere—with the materialand energy resources of the solar system. This isspace age philosophy on a very grand scale.

In spring 1980 Ehricke was the prime lecturerduring an innovative short course on space in-dustrialization held at California State Universityin Northridge. Here, in a number of wonderfultwo-hour sessions, he had the time to properlyintroduce many of the complex ideas that sup-ported his grand vision of the extraterrestrialimperative. He carefully pointed out to an en-thusiastic audience of college students, faculty,and aerospace professionals how space technol-ogy was providing a crucial open-world pathwayfor human development. Ehricke’s lectures in-cluded such visionary concepts as “astropolis”and the “androcell.” Astropolis is his concept fora large urban extraterrestrial facility that orbitsin Earth-Moon (cislunar) space and supportsthe long-term use of the space environment for

110 Einstein, Albert

basic and applied research, as well as for indus-trial development. Ehricke’s androcell conceptis bolder and involves a large human-made worldin space, totally independent of the Earth-Moonsystem. These extraterrestrial city-states, withhuman populations of 100,000 or more, wouldoffer their inhabitants the excitement of multi-gravity-level living at locations throughoutheliocentric space. Just weeks before his deathon December 11, 1984, Ehricke was a featuredspeaker at the national symposium on lunarbases and space activities for the 21st centuryheld that October in Washington, D.C. Despitebeing terminally ill, Krafft traveled across theUnited States from his home in San Diego,California, to give a moving presentation on theimportance of the Moon in creating a polyglobalcivilization for the human race.

Ehricke authored many innovative techni-cal papers on topics that ranged from hydrogenrocket propulsion systems to space industrial-ization and settlement. He received the firstGunter Löser Medal from the InternationalAstronautical Federation in 1956.

5 Einstein, Albert(1879–1955)Swiss-AmericanPhysicist, Philosopher

The most recognizable face in science belongsto the physicist Albert Einstein—a man whoreportedly suffered greatly from being throwninto the celebrity spotlight in the press over hisscientific epiphanies because, according to afriend, the mathematician Arnold Sommerfeld(1868–1951), “every form of vanity was foreignto him.” Einstein credited philosophy as muchas his scientific education with his ability tothink in cosmically new ways, and he relied onphysical relationships instead of mathematics toconceive the ideas that were considered trulygenius.

Einstein was born on March 14, 1879, inWürttemberg, Germany, to a nonobservantJewish family. He reportedly did not speak hisfirst words until he was three years old, going inan instant from complete silence to completesentences. He began school at the HumanisticheGymnasium in Munich, around age six. He alsobegan playing the violin around this time, tak-ing lessons for the next seven years and devel-oping a skill and love for music that he keptfor a lifetime. Never athletic, he acknowledgedas an adult that he had no use for physical ex-ertion, having a fondness only for the sport ofsailing.

As a child, the precocious Einstein was in-doctrinated with religion via the “traditionaleducation-machine,” as he called it in his laterbiographical writings, but discovered sciencearound age 12 and “soon reached the convic-tion that much in the stories of the Bible couldnot be true. The consequence was a positivelyfanatic orgy of freethinking coupled with theimpression that youth is intentionally beingdeceived by the state through lies.” This was, hesaid, “a crushing impression.” The result leftEinstein suspicious of authority and skepticalof the generally accepted truths and norms ofsociety—a skepticism that was according to hiswritings, “an attitude which has never againleft me.”

For the next four years, Einstein read vora-ciously. He was interested in mathematics, par-ticularly differential and integral calculus, andstated that he had “the good fortune of hittingon books which were not too particular in theirlogical rigor but which made up for this by per-mitting the main thoughts to stand out clearlyand synoptically.” One mathematics book inparticular that had an effect on the youngEinstein was a book on Euclidean plane geome-try. But even more important to Einstein thanmathematics was the study of the natural sci-ences. He devoured books on science, particu-larly a multivolume work entitled People’s Books

Einstein, Albert 111

on Natural Science, with, he confessed, “breath-less attention.”

At age 17 Einstein entered the PolytechnicInstitute of Zurich, focusing on mathematicsand physics, where one of his professors wasRudolf Minkowski (1895–1976). But Einsteinwrote that he “neglected mathematics,” becausehe felt that any one discipline in the field could“easily absorb the short lifetime granted to us,”and besides, he was really more interested inscience.

Einstein was critical, however, of an educa-tional system that he felt did more to discour-age freethinking than it did to promote it, eventhough he felt that he was better off in Zurichthan in universities elsewhere. He referred to thesystem’s practices as “coercion” to “cram all thisstuff into one’s mind” for the sole purpose ofpassing examinations. “This coercion had sucha deterring effect,” he wrote, that after passinghis final exams he “found the consideration ofany scientific problems distasteful to me for anentire year.” Einstein believed that this type offorced indoctrination “smothers every truly sci-entific impulse,” and added that “It is, in fact,nothing short of a miracle that the modernmethods of instruction have not yet entirelystrangled the holy curiosity of inquiry.” Einsteingraduated in 1900 with barely passing grades.

After that, Einstein wandered before set-tling into, and settling for, a “temporary” job atthe Swiss Patent Office in Bern in 1902. Thisyear marked two other big events in Einstein’slife. One was his father’s death. The other wasthe birth of his daughter. Einstein’s classmate intheoretical physics from the university, MilevaMaric, with whom he had a long and passionaterelationship, became pregnant in her final yearin school and gave birth to their baby daughter,Leiserl, while staying in the care of her parents.When Mileva went to Bern to help Einstein getsettled, she left the baby with her parents.Within the year Einstein and Mileva were mar-ried, but when they received news that their

daughter had scarlet fever, Mileva returned totend to the child. Leiserl’s fate is unclear—whether she succumbed to scarlet fever, or shesurvived and was adopted, or taken in by one ofMileva’s closest friends, remains a mystery. Butit is known that Mileva returned to Bern alone.The following year, Einstein’s job was made per-manent, and in 1904 his wife had their first son,Hans, who would remain their “only child” un-til Eduard came along six years later.

During this time, Einstein began to write.His ideas on physics were haunting him. “By andby I despaired of the possibility of discoveringthe true laws by means of constructive effortsbased on known facts. How could such a uni-versal principle be found?” he wrote. The knownfacts he referred to were, of course, SIR ISAAC

NEWTON’S theories on physics, which Einsteinfelt were “the dogmatic rigidity [that] prevailedin matters of principles: In the beginning (ifthere was such a thing) God created Newton’slaws of motion together with the necessarymasses and forces.”

The idea that this is all there is did not fitwith his intuition, and yet he needed a sign thatthere was another way. The answer came to himin Maxwell’s theory of electromagnetism. Theelectric industry was a new and exciting one, andEinstein credited James Maxwell (1831–79) asfreeing up the Newtonian “dogmatic faith,” call-ing Maxwell’s work a profound influence on hisability to rethink the problems he strove tosolve.

Within two years, Einstein began to publishhis work. His ideas were revolutionary—the dis-covery of light quantum, which validated thefield of quantum physics introduced by MAX

KARL PLANCK, and his explanations of Brownianmotion, explaining how particles submerged in aliquid will “jitter” as a result of being bombardedwith molecules, which he based on statisticalthermodynamics. He earned a Ph.D. from theUniversity of Zurich for his paper “On a NewDetermination of Molecular Dimensions.”

112 Einstein, Albert

In 1905 Einstein presented a theory that heentitled “On the Electrodynamics of MovingBodies—The special theory of relativity.” Thisidea resulted, he admitted, “from a paradox uponwhich I had already hit at the age of 16: If I pur-sue a beam of light with the velocity of light ina vacuum, I should observe such a beam of lightas a spatially oscillatory electromagnetic field atrest. However, there appears to be no such thing.”

The special theory of relativity shows thattwo observers who are moving with respect toone another will disagree on their observationsof length, time, velocity, and mass. “Space andtime cease to possess an absolute nature,” hewrote. “In space-time, each observer carves outin his own fashion his space and his time.” Hewent on to explain, “Each observer, as his timepasses, discovers, so to speak, new slices of space-time, which appear to him as successive aspectsof the material world, though in reality the en-semble of events constituting space-time existprior to his knowledge of them.”

This theory was based on two postulates.First, that there is no absolute way to measureabsolute motions in space, but instead relativemotion can be obtained on an object as com-pared to another object; and second, that thespeed of light always travels at the same rate.Experiments began to prove the theory, and be-fore long Einstein had the most famous equationof all time—one showing that mass and energyare equivalent:

E 5 mc2.

Einstein credited his ability to come up withthis theory to two sources. “The special theoryof relativity owes its origin to Maxwell’s equa-tions of electromagnetic field,” he said. But, “thetype of critical reasoning which was required forthe discovery . . . was decisively furthered in mycase . . . by the reading of David Hume’s andErnest Mach’s philosophical writings.”

Einstein’s special theory of relativity affectedmany disciplines—physics, philosophy, and, of

course, mathematics. When Minkowski startedusing the theory in his work on world geome-try, Einstein said, “Since the mathematicianshave invaded the theory of relativity, I do notunderstand it myself any more.”

Einstein’s published work succeeded in grab-bing the attention of the universities that hadignored him after his graduation. He left his jobat the patent office and became an associateprofessor at the University of Zurich, then a pro-fessor of theoretical physics in Prague in 1911,then went back to Zurich in 1912 before ac-cepting a research fellowship, in 1914, at theUniversity of Berlin. Here, the absent-mindedProfessor Einstein, who was notorious for losinghis lecture notes, was free to give up lecturingand focus entirely on research.

Between 1905 and 1914, while Einstein wastrying his hand at teaching in various institu-tions, he continued pondering the ideas that ledto the theory of special relativity. His memoirsreveal, “That the special theory of relativity isonly the first step of a necessary developmentbecame completely clear to me only in my ef-forts to represent gravitation in the frameworkof this theory.” He found the special theory “toonarrow.”

Back in 1907, while working at the patentoffice, Einstein had an image in his head of aperson falling through space, and realized thatthe person would not feel his own weight. Hecalled this the “happiest thought of my life.” Heneeded to somehow explain this with the the-ory of relativity, but he could not figure out howto work in the gravity.

In Berlin Einstein finally had the creativefreedom to pursue these thoughts that hadseemed so difficult to him during the past sevenyears because, as he put it, “It was not so easy tofree oneself from the idea that coordinates musthave an immediate metrical meaning.” But thefour-dimensional work that Minkowski pro-duced based on the special theory of relativitywas now starting to make sense, and Einstein

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credited it as indispensable in the theory thatwould be the grandfather of them all: the generaltheory of relativity.

The generalization of the theory of relativ-ity was presented in 1916, and it put forth newlaws of motion and gravitation. The idea thatspace curves around a mass is explained today inhigh school science classes as the “bowlingball on the water bed” experiment: If a bowl-ing ball (a heavy mass) is dropped onto a waterbed, the mattress of the water bed curves aroundthe bowling ball, and when an object of lessmass, for example a marble, is dropped in thevicinity of the bowling ball, it falls toward theheavier mass. Thus, the object of smaller massis attracted to the object of greater mass becauseit is traveling along the curves of space.

Additionally, Einstein imagined a personencapsulated in an elevator in space, noting thatthe person would experience the sensation ofweightlessness until the elevator accelerated up-ward, at which point the person would hit thefloor, experiencing the sensation of gravity; if theperson dropped something during the accelera-tion, the floor would come up to meet it, but itwould also appear that the object “fell” to thefloor. The person would feel no different inthe accelerating elevator in space than he or shewould in the gravitational field on Earth. Theconcept, then, is that gravity and accelerationare the same. Einstein also proposed that light,when passing near the surface of the sun, is de-flected, and that the wavelengths of light fromextremely dense stars, such as white dwarfs, arelengthened.

Einstein was so certain about the simplicityof his theory that he felt no compunction to ex-plain it to those who questioned its validity. Hewrote to Sommerfeld in February 1916, “Of thegeneral theory of relativity you will be con-vinced, once you have studied it. Therefore I amnot going to defend it with a single word.”

A solar eclipse expedition in 1919 organizedby SIR FRANK WATSON DYSON and led by SIR

ARTHUR STANLEY EDDINGTON proved thatEinstein’s ideas about deflected light were cor-rect. Able to compare positions of stars during ablocked-out Sun to their positions when the Sunwas in full view, scientists found that the lighthad been diverted. On November 7, 1919, theTimes of London proclaimed his accomplish-ment with the headline “Revolution in science—New theory of the Universe—Newtonian ideasoverthrown.” According to Sommerfeld, “Weowe the completion of his general theory ofrelativity to his leisure while in Berlin.”

Einstein’s wife left him and returned toSwitzerland with their two children shortly af-ter the family moved to Berlin. Einstein hadrekindled a romantic relationship with his firstcousin, Elsa, and when he began placing de-mands on his wife that did not suit that edu-cated woman’s nature, nor their relationship, sheleft the country and refused a divorce. In 1919the Einsteins finally made their dissolution legal,and Albert married Elsa within a few months.The war was inciting anti-Semitic meetings, andEinstein considered leaving Berlin, but changedhis mind when he attended a meeting at theNauheim Congress of Natural Scientists in 1920and Planck urged him to stay.

In 1921 Einstein received the Barnard Medaland then the Nobel Prize in physics, but surpris-ingly not for his theories on relativity—they werestill too controversial—but rather for his discov-eries from 1905 on quantum light. He sent hisex-wife the money from the prize, which he hadpromised (assuming he would some day win aNobel Prize) as a condition of their divorce, go-ing to great lengths to hide the transaction. In1925 he received the Royal Society’s CopleyMedal, and in 1926, its Gold Medal. After ex-tensive travel—to the United States, Japan,France, Palestine, and South America—the sci-entist eventually collapsed from exhaustion, andhe took the better part of 1928 to recuperate.

In 1933 Einstein returned to the UnitedStates. Sommerfeld writes that “Einstein was

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driven out of Berlin and robbed of his posses-sions,” in 1933, and that “a number of countriesvied for his immigration.” With an offer to teachat Princeton, Einstein, his wife, and his secre-tary (who ultimately worked for him for 50years) stayed in the United States and never re-turned to Germany. He became a U.S. citizenin 1940, giving him dual citizenship in theUnited States and Switzerland.

In August 1948 Einstein’s first wife, Mileva,died after a series of strokes three months after anervous breakdown brought on by repeated con-frontations with their son Eduard, who sufferedfrom violent attacks of schizophrenia.

But Einstein’s scientific brilliance at thispoint was behind him. His work at Princetonwas dedicated to finding one system that ex-plained the subatomic realm of the microcosmwith the macrocosmic universe. His ideas wereperceived as unachievable, and even he recog-nized that he was digging himself into a deeperand deeper hole, writing, “I have locked myselfinto quite hopeless scientific problems.”

Einstein lived a personal life of campaigningfor peace—his last effort was signing a manifestothat urged the elimination of all nuclearweapons. His professional life was one of imag-ination—visualizing problems as they physicallyexist rather than thinking about them purelyfrom a mathematical perspective, and givingtheir solutions with unprecedented simplicity,allowing others to do the detailed work that de-veloped their proof. In explaining his conceptson thinking, he said, “All our thinking is of thisnature of a free play with concepts.”

Einstein wrote his autobiographical notes atthe age of 67, a task he likened to writing hisown obituary. In his notes he gives a glimpse ofhis perception of his place in the world. “Theessential in the being of a man of my type liesprecisely in what he thinks and how he thinks,not in what he does or suffers.”

Einstein’s papers stayed in a basement fileat Princeton until his secretary passed away, at

which point they were willed to the HebrewUniversity in Jerusalem. Included in his docu-ments were letters he had exchanged withMileva, and the discovery that stunned the sci-entific world—it was clear that the two hadcorresponded about scientific theories and prin-ciples for years before they married, and Einsteinhimself wrote to her about “our theory,” and “ourwork” on relativity. These letters have sparkedheated debates in the scientific community, withvarious interpretations about Mileva’s contribu-tions to Einstein’s great discoveries. It is well ac-cepted that her background and education gaveher the access and knowledge to be a collabora-tor, but whether she played a substantial role willmost likely remain a source of contention amongthe scientific community and historians for yearsto come.

The crater Einstein on the surface of theMoon was named in his honor in 1964, andserves as a small reminder of one of the mostbrilliant thinkers in the history of humankind.

5 Euler, Leonhard(1707–1783)SwissMathematician, Physicist

One of the most brilliant and productive math-ematicians of all time, Leonhard Euler developedadvanced analytical techniques to treat thecomplex orbital motion of the Moon and to ef-ficiently determine the orbital paths of newlydiscovered comets. His improved methods incelestial mechanics advanced 18th-century ob-servational astronomy and also supported im-portant improvements in maritime navigationby making possible the preparation of moreaccurate lunar tables.

Leonhard Euler was born on April 15,1707, in Basel, Switzerland. His father was theReverend Paul Euler and his mother wasMargaretha Brucker, a minister’s daughter. While

Euler, Leonhard 115

an undergraduate, Paul Euler became a classmateand friend of the great Swiss mathematicianJohann Bernoulli (1667–1748). With a strongreligious environment influencing his child-hood, Leonhard Euler entered the University ofBasel at the age of 14 to undertake generalstudies in preparation for his own career in theministry. But Bernoulli, then a professor at theuniversity, quickly recognized that the boy wasa mathematical genius. In 1723 Euler completedhis master’s degree in philosophy and then soughthis father’s consent to abandon his ministerialstudy to pursue a new career in mathematics withthe brilliant Bernoulli as his mentor.

The fact that Paul Euler and Bernoulli wereundergraduates at the University of Basel helpedsecure paternal approval for Euler to make thismajor career change. Euler completed his formalstudies in mathematics at the University ofBasel in 1726 and soon began writing the firstof his almost 900 scientific papers and books.As a recent graduate, he won the second-placeprize in mathematics at the Paris Academy in1727 for his innovative paper that addressedthe mathematical arrangement of masts on sail-ing ships. Altogether, Euler would win 12 in-ternational academy prizes in mathematicalcompetition.

Although reluctant to leave Switzerland,Euler departed Basel in April 1727 for St.Petersburg, Russia, to accept a position in thenewly founded Academy of Sciences. The acad-emy in St. Petersburg provided Euler an enrichedworking environment that encouraged him toexplore all aspects of the mathematical sciences.Like many great mathematical figures of the18th century, he applied his talents to theoret-ical astronomy, especially the treatment ofplanetary motions and the orbit of comets.

In January 1734 he married Katharina Gsell,the daughter of the Swiss painter George Gsell,who was then working in St. Petersburg. Thecouple had 13 children, although only five sur-vived infancy. Normally the demands of such a

large family might prove distracting, but Eulerproudly claimed that some of his greatestmathematical inspirations and discoveries camewhile he was holding a baby in his arms and hadother children playing around his feet. In 1735he contracted a severe case of fever that almostproved fatal. Then he experienced eyesightproblems in 1738 and by 1740 had completelylost vision in his right eye.

During his first St. Petersburg period, Euler’sreputation as a mathematician grew. In 1736 hewrote Mechanica (Mechanics)—an importanttreatise that completely transformed Newtoniandynamics into a comprehensive and readily un-derstandable form of mathematical analysis. Hewrote award-winning papers for which he sharedthe Grand Prize of the Paris Academy in both1738 and 1740.

To escape the harsh winters and the growingpolitical turmoil in Russia, Euler accepted aninvitation from the Prussian king Frederick theGreat. Euler traveled to Berlin in 1741 on a mis-sion to revitalize the Prussian Academy ofSciences. During the 25 years he spent in Berlin,Euler wrote numerous papers and importantbooks on algebra, calculus, planetary orbits, andon the motion of the Moon. In 1744 Euler pub-lished Theorium motuum planetarium et cometarium(Theory of the motion of planets and comets)—an influential precursor to the more precise or-bital mechanics work of COMTE JOSEPH LOUIS

LAGRANGE. In 1753 Euler wrote Theoria MotusLunaris (Theory of the lunar motion), his firstattempt to analyze the exact motion of theMoon, a challenging problem that had baffledastronomers and mathematicians since the timeof JOHANNES KEPLER.

By 1759 Euler had assumed the virtual lead-ership of the Berlin Academy of Sciences and hisnumerous contributions to theoretical and ap-plied mathematics were internationally recog-nized. However, because of disagreements withKing Frederick, Euler was never offered the po-sition of academy president. So in 1766 Euler

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returned to St. Petersburg, accepting an invita-tion from the Empress Catherine II (Catherinethe Great). Euler’s departure from Berlin greatlyangered the Prussian king, whose own bumblinghad encouraged the brilliant Swiss mathemati-cian to leave.

Back in St. Petersburg, Euler again experi-enced physical difficulties, but maintained an in-credibly high level of productivity. In 1771 hishome burned to the ground in the great St.Petersburg fire. Later that year, he went com-pletely blind. Despite his blindness, he used hisphenomenal memory to continue to publishpapers and books at an enormous rate. In 1772he published a second, more detailed book onthe Moon’s orbital behavior, Theoria MotuumLunae novo modo pertractata (Theory of lunarmotion, applying new rules)—a monumentalanalytical effort dealing with the difficult three-body problem in orbital mechanics.

Because of Euler’s efforts, 18th-century as-tronomers were able to more quickly and preciselyestimate the orbital path of newly discoveredcomets, using just a few precise observations.These analytical procedures greatly improvedthe business of “comet chasing” by astronomerssuch as CHARLES MESSIER. Euler’s sophisticated

treatment of the Moon’s motion enhancedmaritime navigation by providing detailed lu-nar and planetary tables to assist in longitudedetermination.

What is especially amazing about Euler dur-ing the later part of his life is the level of pro-ductivity he maintained even after he becametotally blind and his first wife, Katharina, died.In 1776 Euler married her half sister, AbigailGsell. He continued to use his phenomenalmemory and some kindly assistance from two ofhis sons to remain history’s most prolific math-ematician until his death in St. Petersburg onSeptember 18, 1783.

But even death did not stop his contributionsto mathematics. He left behind a huge legacy ofunpublished works that kept the printing pressesin Russia busy for another three and a halfdecades. Euler’s mathematical contributions toastronomy and orbital mechanics stretched wellinto the next century. His analytical methodsprepared the way for the great achievements of19th-century astronomy, when mathematiciansworking closely with telescopic astronomers the-oretically predicted the position of, and thensoon discovered previously unseen, solar systemobjects such as Neptune and the minor planets.

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F5 Fleming, Williamina Paton Stevens

(Mina Fleming)(1857–1911)AmericanAstronomer

Williamina Paton Stevens was born in Dundee,Scotland, on May 15, 1857. Her father, a pic-ture framer and early hobbyist in photography,died when she was only seven. She was educatedin local public schools, and at age 14 gave upher education to take a job as a teacher, whichshe pursued until 1877, when at age 20 shemarried James Orr Fleming.

In 1878 the Flemings left Scotland for the United States, immigrating to Boston,Massachusetts. A year later, James Flemingabandoned Mina, as she was known, when shewas pregnant with their first child. MinaFleming was then forced to take a job as ahousemaid, an event that actually proved to beto her great benefit, because her employer wasnone other than the famous professor EDWARD

CHARLES PICKERING, director of the HarvardObservatory.

Pickering had been having problems withhis personnel and had long advocated usingwomen in support positions. In 1881 he hiredFleming to do clerical work in the observatoryand to do mathematical calculations, and she

became the first “computer,” as they were called,at the Harvard Observatory, and the first womanin a group of famous female astronomers thatwould become known as “Pickering’s harem.”Despite her lack of formal higher education,Fleming soon proved adept at both mathematicsand astronomical science.

Under Pickering’s guidance, Fleming de-vised the first system of classifying stars accord-ing to their spectra, determined by holding aprism up to the objective lens of a telescope.Using this system, which was later named afterher, Fleming cataloged more than 10,000 starsduring the next nine years. In 1890 her workwas published in a book entitled The DraperCatalogue of Stellar Spectra.

Fleming was eventually put in charge ofdozens of more women hired to do computationsat the observatory, among them ANNIE JUMP

CANNON, who eventually succeeded Fleming.Fleming was also named editor of all publica-tions issued by the observatory, and in 1898 theHarvard Corporation appointed her as the firstwoman curator of astronomical photographs.Among Fleming’s other accomplishments werethe discovery of 59 nebulae, 10 novae, and morethan 300 variable stars. The eminent Britishastronomer Herbert Hall Turner (1861–1930)once said of Fleming, “Many astronomers are de-servedly proud to have discovered one variable

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star, but [her discoveries are] an achievementbordering on the marvelous.”

In 1906 Fleming became the first Americanwoman to be elected to the Royal AstronomicalSociety. In 1910 she discovered “white dwarfs,”stars in the late stages of their existence that arehot, dense, and appear white or bluish in color.In 1911 Fleming was named an honorary mem-ber of the Astronomical Society of Mexico andthe Astronomical Society of France. That sameyear she also received the Guadalupa AlmendaroMedal and, noting her lack of a graduate degree,Wellesley College named her honorary fellow onastronomy.

Fleming was the most famous female as-tronomer of her time, and one of the first womento have a lunar crater named after her. At thetime of her death from pneumonia in Boston, onMay 21, 1911, she had discovered 10 of the 28known novae and 94 of the 107 known Wolf-Rayet stars—more than any single astronomerin history.

5 Fowler, William Alfred(1911–1995)AmericanPhysicist

“Willy” Fowler, as he was known internationallyby all his colleagues, friends, and associates, wasborn August 9, 1911, in Pittsburgh, Pennsylvania,the first child of John MacLeod Fowler andJennie Summers Watson Fowler. His youngerbrother, Arthur, came next and was soon fol-lowed by a sister, Nelda. Fowler was the pater-nal grandson of an immigrant coal miner fromScotland and an immigrant grocer from NorthernIreland. When he was two years old, Fowler’sfamily moved to Lima, Ohio, where his fatherhad been transferred.

Fowler attended Horace Mann Grade Schooland Lima Central High School, where he was apopular student and an active athlete in baseball,

football, track, and tennis, earning his varsityletter in football his senior year. His teachers en-couraged his interest in engineering and scienceand, perhaps sensing a future for him in highereducation, insisted that he study Latin for fouryears instead of the traditional French andGerman. During this time, when the familyspent their annual vacation back in Pittsburgh,Fowler developed an interest in steam locomo-tives, and would spend hours at the PennsylvaniaRailroad switch yards in Pittsburgh and at localrailroad yards in Lima. This interest became oneof his passionate avocations throughout his life,along with baseball and music, and in 1973he would embark on a 1,500-mile trek fromKhabarovsk to Moscow on the steam-poweredTrans-Siberian Railroad.

In high school Fowler had written aprizewinning essay on how Portland cement wasproduced, and when he enrolled in Ohio StateUniversity he thought he would pursue ceram-ics engineering as his major. However, in hislower-division physics and mathematics courses,Fowler became interested in physics. Upon learn-ing that a new degree field was being offered heswitched his major to engineering physics. In hisjunior year he was elected to the engineeringhonorary society, Tau Beta Pi, and in his sen-ior year he was elected president of the OhioState chapter of that society. He received hisB.S. degree in 1933 and was a classmate of therenowned theoretical physicist Leonard I. Schiff,who became a lifelong friend.

Fowler’s path from Ohio led him straight tothe California Institute of Technology (Caltech)in Pasadena, California, where he became agraduate student at the Kellogg RadiationLaboratory under the renowned Charles C.Lauritsen (1892–1968). Throughout his careerFowler referred to Lauritsen as “the greatest in-fluence in my life,” beginning with Lauritsen’s su-pervision of Fowler’s doctoral thesis, “RadioactiveElements of Low Atomic Number,” which ac-cording to a brief autobiographical piece, Fowler

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described as a study “in which we discoveredmirror nuclei and showed that the nuclear forcesare charged symmetric—the same between twoprotons and between two neutrons whencharged particle Coulomb forces are excluded.”He received his Ph.D. in 1936.

Fowler then joined the Caltech faculty asa research fellow and in 1939 was appointedassistant professor. Prior to World War II hemarried Ardiane Foy Olmsted, with whom hehad two daughters. During the war he spent timein the South Pacific as a civilian with simulatedmilitary rank, doing research and developmentwork on rocket ordnance and proximity fuses.Back at Caltech, he was appointed as full pro-fessor in 1946 and named Institute Professor ofPhysics in 1970.

During 1954–55, Fowler spent a sabbaticalyear as a Fulbright scholar in Cambridge,England, where he worked closely with FredHoyle (1915–2001), who in 1946 had estab-lished the concept of nucleosynthesis in stars.While there, he was joined by ELEANOR

MARGARET PEACHEY BURBIDGE and her husbandGeoffrey, and in 1956 the Burbidges and Hoyleall came to the Kellogg Laboratory at Caltech.The following year, Fowler coauthored one ofthe most famous papers in astrophysics history,“Synthesis of the Elements in the Stars,” whichshowed conclusively that all of the elementsfrom carbon to uranium could be produced bynuclear fission processes in stars, beginning withonly the helium and hydrogen produced in thebig bang, made famous by RALPH ASHER

ALPHER. This paper was cowritten by theBurbidges and Hoyle and is commonly referredto by the authors’ initials, B2FH.

During his 60-year career, Fowler carried outboth theoretical studies to calculate fusion ratesin elements, and experimental studies with par-ticle accelerators to corroborate his theories.He was honored with an array of internationalawards for his lifetime achievements. He wasawarded the medal of merit, presented by

President Harry S. Truman in 1948; elected amember of the National Academy of Sciencesin 1956; awarded the Barnard Medal forMeritorious Service to Science in 1965; desig-nated Benjamin Franklin Fellow of the RoyalSociety of Arts in 1970; awarded the G. UngerVetlesen Prize in 1973; awarded the NationalMedal of Science by President Gerald Ford in1974; designated Associate of the RoyalAstronomical Society in 1975; elected presidentof the American Physical Society in 1976;awarded the Eddington Medal of the RoyalAstronomical Society in 1978; awarded theBruce Gold Medal of the Astronomical Societyof the Pacific in 1979; awarded the Legiond’Honneur from French president FrançoisMitterrand in 1989, and received honorary de-grees from a dozen prestigious universities world-wide. He reached the apogee of his career whenhe was awarded the Nobel Prize in physics in1983 “for his theoretical and experimental stud-ies of the nuclear reactions of importance in theformation of the chemical elements in the uni-verse.” He also collected several awards for hisnonscientific interests in baseball, steam loco-motives, art, music, and outdoor activities.

Fowler was one of the pioneers in the newfield of astrophysics, and his work defining thecreation of new elements inside stars contributedsignificant new knowledge to astronomy and tothe increasingly popular Big Bang theory of theorigin of the universe. A few years before hisdeath he observed, “It is a remarkable fact thathumans, on the basis of experiments and meas-urements carried out in the lab, are able to un-derstand the universe in the early stages of itsevolution, even during the first three minutes ofits existence.”

Fowler’s wife Ardiane died in May 1988,and he remarried in December 1989 to MaryDutcher, a former schoolteacher. He wrote in hisNobel autobiography that after retirement hespent his time attending weekly seminars atCaltech and “in general try to stay out of trouble.”

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On March 14, 1995, Fowler died of naturalcauses in his home in Pasadena, California.

5 Fraunhofer, Joseph von(1787–1826)GermanOptician, Physicist

Early in the 19th century, Joseph von Fraunhoferpioneered the important field of astronomicalspectroscopy. A skilled optician, he developedthe prism spectrometer in about 1814. Then,while using his new instrument, he discoveredmore than 500 mysterious dark lines in the Sun’sspectrum—lines that now carry his name. In1823 he observed similar (but different) lines inthe spectra of other stars, but left it for other sci-entists, among them ROBERT WILHELM BUNSEN

and GUSTAV ROBERT KIRCHHOFF to solve themystery of the “Fraunhofer lines.”

Fraunhofer was born in Straubing, Bavaria,on March 6, 1787. His parents were involved inthe German optical trade, primarily making dec-orative glass. When they died, leaving him anorphan at age 11, his guardians apprenticed himto an optician (mirror maker) in Munich. Whilecompleting this apprenticeship, Fraunhofertaught himself mathematics and physics. Hejoined the Untzschneider Optical Institute, lo-cated near Munich, as an optician in 1806. Helearned quickly from the master glassmakers inthis company and then applied his own talentsto greatly improve the firm’s fortunes. His life-long contributions to the field of optics laid thefoundation for German supremacy in the designand manufacture of quality optical instrumentsin the 19th century.

Fraunhofer’s great contribution to the prac-tice of astronomy occurred quite by accident,while he was pursuing the perfection of theachromatic lens, a lens capable of greatly reduc-ing the undesirable phenomenon of chromaticaberration. As part of this quest, he devised a

clever way to measure the refractive indices ofoptical glass by using the bright yellow emissionline of the chemical element sodium as his ref-erence, or standard. To support his calibrationefforts, in 1814 he created the modern spectro-scope by placing a prism in front of the objectglass of a surveying instrument called a theodo-lite. Using this instrument, he discovered (ormore correctly rediscovered) that the solar spec-trum contained more than 500 dark lines, a pairof which corresponded to the closely spacedbright double emission lines of sodium found inthe yellow portion of the visible spectrum.

In 1802 the British scientist William H.Wollaston (1766–1828) first observed sevendark lines in the solar spectrum. But he did notknow what to make of them and speculated (in-correctly) that the mysterious dark lines weremerely divisions between the colors manifestedby sunlight as it passed through a prism. Workingwith a much better spectroscope 12 years later,Fraunhofer identified 576 dark lines in the solarspectrum and labeled the position of the mostprominent lines with the letters A to K—anomenclature physicists still use today in dis-cussing the Fraunhofer lines. He also observedthat a dark pair of his so-called D-lines in thesolar spectrum corresponded to the position of abrilliant pair of yellow lines in the sodium flamehe produced in his laboratory. However, the truesignificance of this discovery escaped him and,busy making improved lenses, he did not pursuethe intriguing correlation any further. He alsoobserved that the light from other stars whenpassed through his spectroscope produced spec-tra with dark lines that were similar but notidentical to those found in sunlight. But onceagain, Fraunhofer left the great discovery ofastronomical spectroscopy for other scientists.

Fraunhofer was content to note the dark linephenomenon in the solar spectrum and then con-tinue in his quest to design an achromatic ob-jective lens—a task he successfully accomplishedin 1817. He did such high-quality optical work

Fraunhofer, Joseph von 121

that his basic design for this type of lens is stillused by opticians.

In 1821 he built the first diffraction gratingand used the new device instead of a prism toform a spectrum and make more precise meas-urements of the wavelengths corresponding tothe Fraunhofer lines. But again, he did not in-terpret these telltale dark lines as solar absorp-tion lines. In 1859 Bunsen and Kirchhoff wouldfinally put all the facts together and provide as-tronomers with the ability to assess the ele-mental composition of distant stars throughspectroscopy.

Because Fraunhofer did not have a formaluniversity education, the German academiccommunity generally ignored his pioneeringwork in optical physics and astronomical spec-troscopy. At the time, it was considered improper

for a “technician”—no matter how skilled—topresent a scientific paper to a gathering oflearned academicians. Yet 19th-century Germanastronomers, such as FRIEDRICH WILHELM BESSEL,used optical instruments made by Fraunhofer tomake important discoveries. In 1823 Fraunhoferwas appointed as the director of the PhysicsMuseum in Munich and given the honorary titleof professor. He died of tuberculosis in Munich onJune 7, 1826. On his tombstone is inscribed thefollowing Latin epithet: “Approximavit sidera” (incontemporary English: “He reached for the stars.”)

In his honor, scientists now refer to the dark(absorption) lines in the visible portion of theSun’s spectrum as Fraunhofer lines. These linesare the phenomenological basis of astronomicalspectroscopy and give scientists the ability tolearn what stars are really made of.

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G5 Galilei, Galileo

(1564–1642)ItalianAstronomer, Mathematician, Physicist

As the incomparable “founding father of modernscience,” Galileo Galilei used his own version ofthe newly invented telescope to make detailedastronomical observations that ignited the sci-entific revolution of the 17th century. In 1610he announced some of his early telescopic find-ings in the publication Sidereus Nuncius (Thestarry messenger)—including his discovery ofthe four major moons of Jupiter, now called theGalilean satellites in his honor. Their orbital be-havior, like a miniature solar system, stimulatedhis enthusiastic support for the heliocentric cos-mology of NICOLAS COPERNICUS. Unfortunately,this scientific position led to a direct clash withecclesiastical authorities bent on retainingPtolemaic cosmology for a number of politicaland social reasons. By 1632 this conflict earnedthe fiery Galileo an Inquisition trial at whichhe was found guilty of heresy for advocatingCopernican cosmology. Because of his advanc-ing age and blindness, he was confined to housearrest for the remainder of his life. This unjustincarceration could not prevent his brilliant sci-entific work in astronomy, physics, and mathe-matics from creating the revolution in thinking

now known as the scientific method—an en-tirely new way of looking at the universe andone of the greatest contributions of Western civ-ilization to the human race.

The Italian astronomer, mathematician, andphysicist Galileo Galilei was born in Pisa onFebruary 15, 1564. Galileo is commonly knownby his first name only. His father, VincenzoGalilei (ca. 1520–91) was a scholar and musi-cian. When Galileo entered the University ofPisa in 1581, his father encouraged him to studymedicine. However, his inquisitive mind soonbecame more interested in physics and mathe-matics than medicine. While still a medical stu-dent, he attended church services one Sundayand noticed a chandelier swinging in the breeze.He began to time its swinging motion using hisown pulse as a crude clock. When he returnedhome, he immediately set up an experiment thatrevealed the pendulum principle. After just twoyears of study, Galileo abandoned medicineand focused on mathematics and science. Thischange in career pathways also changed the his-tory of modern science.

In 1585 Galileo left the university withoutreceiving a degree to focus his activities on thephysics of fluids and solid bodies. The followingyear, he published a small booklet that describedthe clever hydrostatic balance he invented todetermine relative densities. This was Galileo’s

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first splash into science and it brought him at-tention from the academic world.

In 1589 Galileo became a mathematics pro-fessor at the University of Pisa. He was a bril-

liant lecturer and students came from all overEurope to attend his classrooms. Galileo oftenused his tenacity, sharp wit, and biting sarcasmto win philosophical arguments against his uni-versity colleagues. His fiery, unyielding person-ality earned him the nickname “the Wrangler.”While his personal characteristics drove Galileoto many great discoveries, they also left a trailof bitter opponents who waited patiently for himto stumble so they could exact their revenge. By1592 he had sufficiently offended his academiccolleagues at the University of Pisa so that uni-versity officials chose not to renew his teachingcontract.

In the late 16th century, European profes-sors usually taught physics (then called “naturalphilosophy”) as an extension of Aristotelian phi-losophy and not as a science, based on observa-tion and experimentation, as it is practicedtoday. Through his skillful use of mathematics andinnovative experiments, Galileo singlehandedlychanged that approach. The motion of fallingobjects and projectiles intrigued him, and his sci-entific experiments constantly challenged the2,000-year tradition of ancient Greek learning.

ARISTOTLE stated that heavy objects wouldfall faster than lighter objects. Galileo disagreedand declared that, except for air resistance, thetwo objects would fall at the same rate regard-less of their mass. It is not certain whether heactually performed the legendary musket ball–cannonball drop experiment from the LeaningTower of Pisa to prove this point. However, hedid conduct a sufficient number of experimentswith objects on inclined planes to upsetAristotelian physics and establish the science ofmechanics.

Throughout his life, Galileo was limited inhis motion experiments by an inability to accu-rately measure small increments of time. Despitethis impediment, he conducted many importantexperiments that produced remarkable insightsinto the physics of free fall and projectile mo-tion. A century later, SIR ISAAC NEWTON would

A 1640 portrait of the incomparable “FoundingFather of Modern Science,” Galileo Galilei. This fieryItalian astronomer, physicist, and mathematicianused his own version of the newly inventedtelescope to make detailed astronomicalobservations that flamed the scientific revolution inthe 17th century. In 1610 his Sidereus Nuncius (Thestarry messenger), proclaimed the discovery of thefour major moons of Jupiter—now called theGalilean satellites in his honor. Because theybehaved like a miniature solar system, Galileo threwhis enthusiastic support behind the controversialheliocentric cosmology of Nicolas Copernicus.Unfortunately, this scientific position ultimatelyearned him a conviction for heresy in 1632 andconfinement to house arrest for the remainder of hislife. (Courtesy of the National Aeronautics andSpace Administration [NASA])

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build upon Galileo’s pioneering work to createhis universal law of gravitation and three lawsof motion.

As previously mentioned, by 1592 Galileo’santi-Aristotelian research and abrasive behaviorhad sufficiently offended his colleagues at theUniversity of Pisa to the point that universityofficials not so politely invited him to teach else-where. So Galileo moved to the University ofPadua—the main institution of higher learningfor the powerful Republic of Venice. This uni-versity had a more lenient policy of academicfreedom, encouraged in part by the progressiveVenetian government. Galileo eagerly acceptedan appointment as a professor of mathematics.He even wrote a special treatise on mechanicsto accompany his lectures. In Padua he taughtcourses on Euclidian geometry and on astron-omy. The late 16th-century astronomy coursesat Padua were primarily intended for medicalstudents who needed to learn enough Ptolemaicastronomy to practice medical astrology. Italianphysicians of the High Renaissance were ex-pected to “consult with the stars” as part of treat-ing patients. Such academic duties gave Galileohis first formal contact with astronomy, and thepractice of science would never be the same.

In 1597 the German astronomer JOHANNES

KEPLER, gave Galileo a copy of Copernicus’sbook—even though the book was then officiallybanned in Italy. Up to this point in his lifeGalileo had not been seriously interested inastronomy, but in this “forbidden” book he dis-covered heliocentric cosmology and immedi-ately embraced it. Galileo and Kepler continuedto correspond until about 1610.

Almost coinciding with his interest inCopernican theory, Galileo experienced severalimportant changes in his personal life while liv-ing in Padua. The first of his three out-of-wed-lock children by Marina Gamba of Venice wasborn in Padua on August 21, 1600. She wasnamed Virginia Galilei and would later assumethe name Sister Maria Celeste. His second

daughter, Livia Galilei, was born in Padua in1601, and his son, Vincenzio Galilei, was alsoborn in Padua in 1604. Galileo did not marryhis children’s mother because in 17th-centuryItaly, the relationship was considered inappro-priate—Gamba was much younger than Galileoand from a socially inferior family. Yet Galileoalways remained financially responsible to herand his children—although he did so always un-der extreme financial stress. When his fatherdied at a young age in 1591, Galileo followedcontemporary social custom and assumed fa-milial financial responsibility by providing asubstantial dowry for his sister, Virginia Galilei.This constant drain on his meager salary as amathematics professor made him resort to tu-toring and casting horoscopes to make financialends meet.

Between 1604 and 1605, Galileo performedhis first public work involving astronomy. Heobserved the supernova of 1604 in the constel-lation Ophiuchus and used the phenomenon torefute the cherished Aristotelian belief that theheavens were immutable (that is, unchange-able). He boldly delivered this challenge onAristotle’s doctrine in a series of public lectures.Unfortunately, these well-attended lecturesbrought him into direct conflict with the uni-versity’s pro-Aristotelian philosophy professors.

In 1609, Galileo learned that a new opticalinstrument (called a magnifying tube) had justbeen invented in Holland. Within six months,he devised his own version of the instrument,then in 1610 he turned this improved telescopeto the heavens and started the age of telescopicastronomy. With his crude instrument, he madea series of astounding discoveries, including theexistance of mountains on the Moon, many newstars, and four moons orbiting Jupiter. His pub-lished discoveries in The starry messenger stim-ulated both enthusiasm and anger. The moonsorbiting Jupiter proved that not all heavenlybodies revolve around Earth; direct observa-tional evidence for the Copernican model.

Personally unable to continue teaching theAristotelian doctrine at the university becauseof the overwhelming evidence against it, Galileoleft Padua in 1610 and went to Florence wherehe accepted an appointment as chief mathe-matician and philosopher to the grand duke ofTuscany, Cosimo II. By now Galileo’s fame hadspread throughout Italy and the rest of Europe.His telescopes were in demand and he obliginglyprovided them to selected astronomers through-out Europe, including Kepler. In 1611 he proudlytook his telescope to Rome and let church offi-cials personally observe some of his discoveries.While in Rome, he also became a member ofthe prestigious Accademia dei Lincei (LynceanAcademy), the first true scientific society, foundedin 1603.

In 1613 Galileo published his “Letters onSunspots” through the academy. He used the ex-istence and motion of sunspots to demonstratethat the Sun itself changes, again attackingAristotle’s doctrine of the immutability of theheavens. In so doing, he also openly endorsedthe Copernican model. This started Galileo’slong and bitter fight with church authorities.

Above all, Galileo believed in the freedomof scientific inquiry. Late in 1615 Galileowent to Rome and publicly argued for theCopernican model. Angered by Galileo’s opendefiance, Pope Paul V (1605–21) formed a spe-cial commission to review the theory of Earth’smotion. Dutifully, the unscientific commissionconcluded that the Copernican theory wascontrary to biblical teachings and possiblyeven represented a form of heresy. In lateFebruary 1616 Cardinal Robert Bellarmine of-ficially warned Galileo to abandon his supportof the Copernican hypothesis or face harshpunishment.

The cardinal’s stern message toned downGalileo’s behavior—at least for a few years. In1623 Galileo published Il saggiatore (The as-sayer), a book in which he discussed the princi-ples for scientific research, but carefully avoided

support for Copernican theory. He even dedi-cated the book to his lifelong friend, the newpope, Urban VIII (1623–44).

However, in 1632 Galileo pushed his friend-ship with the pope to the limit by publishing Dia-logue on the Two Chief World Systems. In thismasterful satirical work, Galileo uses two maincharacters to present scientific arguments, con-cerning the Ptolemaic and Copernican world-views, to an intelligent third person. Galileo’sfictional Copernican, Salviati, cleverly winsthese lengthy arguments. In contrast, Galileopresents Aristotelian thinking and the Ptolemaicsystem through an ineffective character he callsSimplicio. The pope regarded Galileo’s fictionalSimplicio as an insulting personal caricature, andwithin months the Inquisition summonedGalileo to Rome. Under threat of execution, theaging Italian scientist publicly retracted his sup-port for the Copernican model on June 22, 1633.Tradition suggests that a feeble, but defiant,Galileo whispered these words as he rose from hisknees after renouncing Copernican cosmology:“Eppur si muove.” (“And yet it moves.”)

Instead of torture and death, the Inquisitionsentenced him to life in prison—a more lenientterm that he was allowed to serve under housearrest at his villa in Arceti near Florence. Theecclesiastical authorities also banned his bookDialogue. However, Galileo’s loyal supporterssmuggled copies out of Italy, and soon itspro-Copernican message was spreading acrossEurope.

While under house arrest, Galileo spenthis final years working on less controversialphysics. In 1638 he published Discourses andMathematical Demonstrations Relating to Two NewSciences. Fearing for his life, he carefully avoidedastronomy in this seminal work and concen-trated his creative energies on summarizing thescience of mechanics, including uniform accel-eration, free fall, and projectile motion.

Through Galileo’s pioneering work andpersonal sacrifice, the Scientific Revolution

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ultimately prevailed over misguided adherenceto centuries of Aristotelian philosophy. Henever really opposed the church nor its reli-gious teachings. He did, however, come outstrongly in favor of the freedom of scientificinquiry and he would not tolerate supposedlylearned academicians or ecclesiastics whoremained mentally blind to demonstrablescientific facts. Physical blindness struck thebrilliant scientist in 1638, and he died at homeon December 25, 1642, the same day Newtonwas born.

Some three and a half centuries later, onOctober 31, 1992, Pope John Paul II formally re-tracted the sentence of heresy passed on Galileoby the Inquisition. As the pope was announcingthis official retraction, a NASA spacecraftnamed Galileo was speeding through interplan-etary space on course for its successful ren-dezvous mission with Jupiter and the giantplanet’s family of interesting moons, includingthe Galilean moons that helped establish theScientific Revolution.

5 Galle, Johann Gottfried(1812–1910)GermanAstronomer

By good fortune and some careful telescopicviewing, Johann Gottfried Galle became thefirst person to observe and properly identify theplanet Neptune. Acting upon a recommenda-tion from URBAIN-JEAN-JOSEPH LEVERRIER,Galle began a special telescopic observation atthe Berlin Observatory on September 23,1846. His search quickly revealed the newplanet precisely in the region of the night skypredicted by Leverrier’s calculations. Improvedmathematical techniques helped Galle andLeverrier convert subtle perturbations in theorbit of Uranus into one of the major discov-eries of 19th-century astronomy.

Galle was born in Pabsthaus, Germany, onJune 9, 1812. He received his early educationat the Wittenberg Gymnasium (secondaryschool) and then studied mathematics andphysics at the Berlin University. After graduat-ing from the university in 1833, Galle taughtmathematics in the gymnasiums at Guben andBerlin. Then, in 1835, his former professorJohann Franz Encke (1791–1865) invited Galleto become his assistant at the newly foundedBerlin Observatory.

Galle proved to be a skilled telescopic as-tronomer. In 1838 he discovered the C or“crêpe” ring of Saturn. He was also an avid comethunter, and during winter 1839–40 Galle dis-covered three new comets. In 1846 good fortunesmiled on Galle and allowed him to play amajor role in one of the most important mo-ments in the history of planetary astronomy.Independent of the British astronomer JOHN

COUCH ADAMS, the French astronomer andmathematician Urbain-Jean-Joseph Leverrier,studied the perturbations in the orbit of Uranusand made his own mathematical predictionsconcerning the location of another planet be-yond Uranus. Leverrier corresponded with Galleon September 18, 1846, and asked the Germanastronomer to investigate a section of the nightsky to confirm his mathematical prediction thatthere was a planet beyond Uranus.

Upon receipt of Leverrier’s letter, Galleand his assistant, Heinrich Ludwig d’Arrest(1822–75), immediately began searching theportion of the sky recommended by the Frenchmathematical astronomer. D’Arrest also sug-gested to Galle that they use Encke’s most recentstar chart to assist in the search for the elusivetrans-Uranian planet. In less than an hour Galledetected a “star” that was not on Encke’s latestchart. A good scientist, Galle waited 24 hours toconfirm that this celestial object was indeedthe planet Neptune. On the following night(September 24), Galle again observed the objectand carefully compared its motion relative to that

of the so-called fixed stars. There was no longerany question: The change in its position clearlyindicated that this “wandering light” was anotherplanet.

Galle discovered Neptune pretty much inthe position predicted by Leverrier’s calculations.He immediately wrote to Leverrier, informinghim of the discovery and thanking him for thesuggestion on where to search. The telescopicdiscovery of Neptune by Johann Galle onSeptember 23, 1846, is perhaps the greatest ex-ample of the marriage of mathematics and as-tronomy in the 19th century. Subtle perturbationsin the calculated orbit of Uranus suggested tomathematicians and astronomers that one ormore planets could lie beyond. Yet this discoverybecame one of the biggest controversies in thescientific community. Today, credit for the com-bined predictive and observational discovery ofNeptune is awarded jointly to Adams, Galle, andLeverrier.

In 1851 Galle accepted a position as the di-rector of the Breslau Observatory and remainedthere until his retirement in 1897. He made ad-ditional contributions to astronomy by focusinghis attention on determining the mean distancefrom Earth to the Sun—an important referencedistance called the astronomical unit (AU).Astronomers relied on the transits of Venusacross the face of the Sun to make an estimateof the astronomical unit. At the time, this was arather difficult measurement, since astronomershad to determine precisely the moment of firstcontact.

However, in 1872 Galle suggested a moreaccurate and reliable way of measuring the scale of the solar system. He recommended thatastronomers use the asteroids whose orbits comevery close to Earth to measure solar parallax.Galle reasoned that the minor planets offeredmore precise, pointlike images and their largenumber provided frequent favorable opposi-tions. In an effort to demonstrate and refine thistechnique, Galle observed the asteroid Flora in

1873. Astronomers SIR DAVID GILL and SIR

HAROLD SPENCER JONES greatly improved meas-urement of the Earth-Sun distance using Galle’ssuggestion.

Of the three codiscoverers of Neptune, onlyGalle survived until 1896 to receive congratula-tions from the international astronomical com-munity as it celebrated the 50th anniversary oftheir great achievement. He died on July 10,1910, in Potsdam, Germany.

5 Gamow, George (Georgi Antonovich)(1904–1968)Ukrainian/AmericanPhysicist, Cosmologist

A successful nuclear physicist, cosmologist, andastrophysicist, George Gamow was a pioneeringproponent of the big bang theory, which boldlyspeculated that the universe began with a hugeancient explosion. As part of this hypothesis, healso participated in the prediction of the exis-tence of a telltale cosmic microwave back-ground, observational evidence for which wasdiscovered by ARNO ALLEN PENZIAS and ROBERT

WOODROW WILSON in the early 1960s.George Gamow was born on March 4, 1904,

in the city of Odessa in the Ukraine. His grand-father was a general in the Russian army and hisfather was a teacher. On his 13th birthday,Gamow received a telescope—a life-changinggift that introduced him to astronomy andhelped him decide on a career in physics. Havingsurvived the Russian Revolution, he enteredNovorossysky University in 1922 at 18 years ofage. He soon transferred to the Universityof Leningrad (now called the University ofSt. Petersburg), where he studied physics, math-ematics, and cosmology. Gamow completed hisPh.D. in 1928, the same year he proposed thatalpha decay could be explained by the phenom-enon of the quantum mechanical tunneling ofalpha particles through the nuclear potential

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barrier in the atomic nucleus. This innovativework represented the first successful extensionof quantum mechanics to the atomic nucleus.

As a bright young nuclear physicist, Gamowperformed postdoctoral research throughoutEurope, visiting the University of Göttingen inGermany, working with Niels Bohr (1885–1962)in Copenhagen, Denmark, and studying be-side Ernest Rutherford (1871–1937) at the

Cavendish Laboratory in Cambridge, England.In 1931 he was summoned back to the SovietUnion to serve as a professor of physics atLeningrad University. However, after living inwestern Europe for several years, he found life inStalinist Russia not to his liking. A highly cre-ative individual, he obtained permission to at-tend the 1933 International Solvay Congress inBrussels, Belgium, and then never returned toStalin’s Russia. He emigrated from Europe to theUnited States in 1934, accepting a facultyposition at George Washington University, inWashington, D.C., and becoming a U.S. citizen.In 1936 he collaborated with the Hungarian-American physicist Edward Teller (1908–2003)in developing a theory to explain beta decay, theprocess whereby the nucleus emits an electron.

At this point in his career, Gamow beganexploring relationships between cosmology andnuclear processes. He used his knowledge of nu-clear physics to interpret the processes takingplace in various types of stars. In 1942, again incollaboration with Teller, Gamow developed atheory about the thermonuclear reactions andinternal structures within red giant stars. Theseefforts also led Gamow to conclude that theSun’s energy results from thermonuclear reac-tions. He was also an ardent supporter of EDWIN

POWELL HUBBLE’S expanding universe theory, anastrophysical hypothesis that made him an earlyand strong advocate of the Big Bang theory.

RALPH ASHER ALPHER, a student underGamow, introduced the Big Bang cosmologywhich Gamow had published in the 1948paper “The Origin of the Chemical Elements.”He based some of this work on cosmology con-cepts previously suggested by ABBE-GEORGES-ÉDOUARD LEMAÎTRE. Starting with the explosionof Lemaître’s “cosmic egg,” Gamow proposed amethod of thermonuclear reactions by which thevarious elements could emerge from a primor-dial mixture of nuclear particles that he calledthe ylem. Although later nucleosynthesis mod-els introduced by WILLIAM ALFRED FOWLER and

A successful nuclear physicist, cosmologist, andastrophysicist, George Gamow pioneered the big banghypothesis in the late 1940s. Building up thepreliminary concepts of others, he boldly concludedthat the universe began with a huge explosion—sarcastically called the “big bang” by his detractors.Gamow further suggested that the modern remnants ofthis ancient explosion would be a curtainlikemicrowave (“cold light”) signal at the very edge of theobservable universe. Almost two decades before theevent, Gamow had brilliantly anticipated the detectionof this telltale cosmic microwave background by theNobel Prize–winning radio astronomers Arno Penziasand Robert W. Wilson in 1964. (AIP Emilio SegrèVisual Archives)

other astrophysicists would supersede this work,Gamow’s pioneering investigations provided animportant starting point. Perhaps the most sig-nificant postulation to emerge from these effortswas the prediction that the Big Bang would pro-duce a uniform cosmic microwave background—a lingering remnant at the edge of the observ-able universe. The discovery of this cosmicmicrowave background in 1964 by Penzias andWilson renewed interest in the Big Bang cos-mology and provided scientific evidence thatstrongly supported an ancient explosion hy-pothesis. In his 1952 book, Creation of theUniverse, Gamow presented a detailed discussionof these concepts in cosmology.

Just after James Watson (born 1928) andFrancis Crick (1916–2004) proposed their DNAmodel in 1953, Gamow turned his scientific in-terests from the physics taking place at start ofthe universe to the biophysical nature of life. Hepublished several papers on the storage and trans-fer of information in living cells. While his pre-cise details were not terribly accurate by today’slevel of understanding in the field of genetics, hedid introduce the important concept of “geneticcode”—a fundamental idea confirmed by subse-quent experimental investigations.

In 1956 Gamow became a faculty memberat the University of Colorado in Boulder and re-mained at that institution for the rest of his life.He was a prolific writer who produced highlytechnical books, such as the Structure of AtomicNuclei and Nuclear Transformations (1937), andalso very popular books about science for gen-eral audiences. Several of his most popular bookswere Mr. Tompkins in Wonderland (1936), One,Two, and Three . . . Infinity (1947), and A StarCalled the Sun (1964).

George Gamow was elected to the RoyalDanish Academy of Sciences in 1950 and the U.S.National Academy of Sciences in 1953. TheUnited Nations Educational, Scientific, andCultural Organization (UNESCO) bestowed itsKalinga Prize on Gamow in 1956 for his literary

efforts that popularized modern science around theworld. He died in Boulder on August 19, 1968.

5 Giacconi, Riccardo(1931– )Italian/AmericanAstrophysicist

Using special instruments carried into spaceon sounding rockets and satellites, RiccardoGiacconi helped establish the exciting new fieldof X-ray astronomy. This great astrophysical ad-venture began quite by accident in June 1962,when Giacconi’s team of scientists placed a spe-cially designed instrument package on a sound-ing rocket. As the rocket climbed above Earth’ssensible atmosphere over White Sands, NewMexico, the instruments unexpectedly detectedthe first cosmic X-ray source—that is, a sourceof X-rays from beyond the solar system. Sub-sequently named Scorpius X-1, this “X-ray star”is the brightest of all nontransient X-ray sourcesever discovered. He shared the 2002 Nobel Prizein physics for his pioneering contributions to as-trophysics.

Riccardo Giacconi was born in Milan, Italy,on October 6, 1931. He earned his Ph.D. degreein cosmic ray physics at the University of Milanin 1956 and then immigrated to the UnitedStates to accept a position as a research associ-ate at Indiana University in Bloomington. In1959 he moved to the Boston area to joinAmerican Science and Engineering, a small sci-entific research firm established by scientistsfrom the Massachusetts Institute of Technology,where he began his pioneering activities in X-ray astronomy.

Collaborating with Professor BRUNO BENE-DETTO ROSSI at the Massachusetts Institute ofTechnology and other researchers in the early1960s, Giacconi designed novel X-ray detectioninstruments for use on sounding rockets andeventually spacecraft. His June 1962 experiment

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proved especially significant when his team, insearch of possible solar-induced X-ray emissionsfrom the lunar surface, accidentally detected thefirst known X-ray source outside the solar systemfrom Scorpius X-1. Previous rocket-borne experi-ments by personnel from the U.S. Naval ResearchLaboratory that started in 1949 had detected X-rays from the Sun, but the new X-ray star was the

first source of X-rays known to exist beyond thesolar system. This fortuitous discovery is often re-garded as the beginning of X-ray astronomy, animportant field within high-energy astrophysics.

Because Earth’s atmosphere absorbs X-rays,instruments to detect and observe X-rays pro-duced by astronomical phenomena must beplaced in space high above the sensible atmos-phere. Sounding rockets provide a brief (typi-cally just a few minutes) way of searching forcosmic X-ray sources, while specially instru-mented orbiting observatories provide scientistswith a much longer period of time to conductall-sky surveys and detailed investigations of in-teresting X-ray sources. Astrophysicists investi-gate X-ray emissions because they provide aunique insight into some of the most violent andenergetic processes taking place in the universe.

In the mid-1960s, as an executive vice pres-ident and senior scientist at American Scienceand Engineering, Giacconi headed the scientificteam that constructed the first imaging X-ray tel-escope. In this novel instrument, incoming X-rays graze or ricochet off precisely designed andshaped surfaces and then collect at a specificplace called the focal point. The first such de-vice flew into space on a sounding rocket in 1965and made captured images of X-ray hot spots inthe upper atmosphere of the Sun. The NationalAeronautics and Space Administration (NASA)used greatly improved versions of this type of in-strument on the Chandra X-ray Observatory.

The following analogy illustrates the signif-icance of Giacconi’s efforts in X-ray astronomyand also serves as a graphic testament to the rapidrate of progress in astronomy brought on by thespace age. By historic coincidence, Giacconi’sfirst, relatively crude X-ray telescope was ap-proximately the same length and diameter as theastronomical telescope used by GALILEO GALILEI

in 1610. Over a period of about four centuries,optical telescopes improved in sensitivity by 100million times, as their technology matured fromGalileo’s first telescope to the capability of

The Italian-American astrophysicist Riccardo Giacconias he appeared in the mid-1960s, during that excitingresearch period when he helped establish thefoundations for modern X-ray astronomy. His firstmajor achievement occurred in 1962 when hecollaborated with Bruno Rossi and placed a new typeof X-ray detection instrument on a sounding rocket thatfortuitously discovered the first cosmic X-ray sourcecalled Scorpius X-1. In the 1970s he supervised thedevelopment of several X-ray astronomy spacecraft forNASA. For these pioneering contributions toastrophysics and to X-ray astronomy, he shared the2002 Nobel Prize in physics. (AIP Emilio Segrè VisualArchives, Physics Today Collection)

NASA’s Hubble Space Telescope. About 40 yearsafter Giacconi tested the first X-ray telescope ona sounding rocket, NASA’s magnificent ChandraX-ray Observatory provided scientists with a leapin measurement sensitivity of about 100 million.Much as Galileo’s optical telescope revolution-ized observational astronomy in the 17th century,Giacconi’s X-ray telescope triggered a modernrevolution in high-energy astrophysics.

Giacconi functioned well both as a skilledastrophysicist and as a successful scientific man-ager capable of overseeing the execution of large,complex scientific projects. He envisioned andthen supervised development of two importantorbiting X-ray observatories: the Uhuru satelliteand the Einstein X-Ray Observatory.

In the late 1960s his group at AmericanScience and Engineering supported NASA inthe design, construction, and operation of theUhuru satellite—the first orbiting observatorydedicated to making surveys of the X-ray sky.Uhuru, also known as Small Astronomical Satellite1, was launched from the San Marco platformoff the coast of Kenya on December 12, 1970.By coincidence, that date marked the seventhanniversary of Kenyan independence, so NASAcalled this satellite Uhuru, which is the Swahiliword for “freedom.” The well-designed space-craft operated for more than three years and de-tected 339 X-ray sources, many of which turnedout to be due to matter from companion starsbeing pulled at extremely high velocity into sus-pected black holes or superdense neutron stars.With this successful spacecraft, Giacconi’s teamfirmly established X-ray astronomy as an excit-ing new astronomical field.

In 1973 Giacconi moved his X-ray astron-omy team to the Harvard-Smithsonian Centerfor Astrophysics, headquartered in Cambridge,Massachusetts. There, he supervised the devel-opment of a new satellite for NASA called HighEnergy Astronomical Observatory 2 (HEAO-2).Following a successful launch in November 1978,NASA renamed the spacecraft the Einstein

X-Ray Observatory. It was the first orbiting ob-servatory to use the grazing incidence X-ray tel-escope (a concept initially proposed by Giacconiin 1960) to produce detailed images of cosmicX-ray sources. The Einstein X-Ray Observatoryoperated until April 1981 and produced morethan 7,000 images of various extended X-raysources, such as clusters of galaxies and super-nova remnants.

Giacconi’s display of superior scientific man-agement skills during the Uhuru and Einsteinobservatory projects secured his 1981 appoint-ment as the first director of the Space TelescopeScience Institute—the astronomical researchcenter on the Homewood campus of JohnsHopkins University, in Maryland, responsible foroperating NASA’s Hubble Space Telescope. From1993 to 1999 Giacconi served as the directorgeneral of the European Southern Observatory(ESO) in Garching, Germany. This was his firstscientific leadership role involving ground-basedastronomical facilities. Prior to leaving thisEuropean intergovernmental organization, hesuccessfully saw the “first light” for ESO’s newVery Large Telescope in the Southern Hemisphereon Cerro Paranal in Chile.

In July 1999 Giacconi returned to theUnited States to become president and chiefexecutive officer of Associated Universities,Inc.—the Washington, D.C.–headquartered not-for-profit scientific management corporationthat operates the National Radio AstronomyObservatory in cooperation with the NationalScience Foundation. In October 2002 the NobelCommittee awarded Giacconi one-half of thatyear’s Nobel Prize in physics for his pioneeringcontributions to astrophysics.

A renowned scientist and manager, Giacconihas received numerous awards, including theBruce Gold Medal from the AstronomicalSociety of the Pacific (1981) and the GoldMedal of the Royal Astronomical Society inLondon (1982). He is the author of more than200 scientific publications that deal with the

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X-ray universe, ranging from black hole candi-dates to distant clusters of galaxies.

5 Gill, Sir David(1843–1914)BritishAstronomer

Sir David Gill was the Scottish watchmakerturned astronomer who passionately pursued themeasurement of solar parallax. His careful ob-servations, often involving travel with his wife,Lady Isabel Gill, to remote regions of Earth, es-tablished a value of the astronomical unit thatserved as the international reference until 1968.For example, in 1877 the couple lived for sixmonths on tiny Ascension Island, in the middleof the South Atlantic, just so Gill could estimatea value for solar parallax by observing Mars dur-ing its closest approach. The couple also residedin South Africa for 28 years so he could serve asthe British royal astronomer in charge of theCape of Good Hope Observatory.

Gill was born in Aberdeen, Scotland, onJune 12, 1843. From 1858 to 1860 he studied atthe Marischal College of the University ofAberdeen, but left without a degree because offamily circumstances: As the eldest survivingson, he abandoned college and trained to be awatchmaker, so he could take over his aging fa-ther’s business. However, while at MarischalCollege, Gill had the brilliant Scottish physicistJames Clerk Maxwell (1831–79) as his professorof natural philosophy. Maxwell’s lectures greatlyinspired Gill, and the young watchmaker wouldultimately pursue a career in science.

By good fortune, his activities in precisiontimekeeping led him directly into a career in as-tronomy. While operating his watch- and clock-making business, Gill developed a great facilitywith precision instruments. As a hobby, he re-stored an old, abandoned transit telescope inorder to provide the city of Aberdeen with ac-

curate time. He also purchased a 12-inch re-flecting telescope and modified the device totake photographs. Gill’s excellent photograph ofthe Moon taken on May 18, 1869, soon caughtthe attention of the young Lord Lindsay, whowas persuading his father, the earl of Crawford,to build him a private astronomical observa-tory. After brief negotiations, Gill abandonedthe family watchmaking business in 1872 to be-come the director of Lindsay’s observatory nearAberdeen. As a competent instrument makerand self-educated observational astronomer, Gillset about the task of designing, equipping, andoperating Lord Lindsay’s observatory at DunEcht, Scotland.

His years as a privately employed astronomerat Dun Echt brought Gill in contact with the mostprominent astronomers in Europe. The work alsoprepared him well for the next step in his careeras a professional astronomer, especially his expe-rience with precision measurements using the he-liometer. In the 19th century astronomers usedthis (now obsolete) instrument to measure theparallax of stars and the angular diameter of plan-ets. David Gill became a world-recognized expertin the use of the heliometer—an instrument heapplied relentlessly in pursuit of his lifelong questto precisely measure solar parallax.

Astronomers define solar parallax as the an-gle subtended by Earth’s equatorial radius whenEarth is observed from the center of the Sun—that is, at a distance of one astronomical unit.The astronomical unit (149,600,000 kilometers)is the basic reference distance in solar system as-tronomy. By international agreement, the solarparallax is approximately 8.794 arc seconds.

Sponsored by Lord Lindsay, Gill participatedin an astronomical expedition to Mauritius in1874 to observe the transit of Venus. He took 50precision chronometers on a long sea voyagearound the southern tip of Africa to Mauritius,a small island in the Indian Ocean east ofMadagascar. Gill focused on providing precisetiming for the other astronomers.

A planetary transit takes place when one ce-lestial object moves across the face of anothercelestial object of larger diameter—such asMercury or Venus moving across the face of theSun as viewed by an observer from Earth. The1874 transit of Venus provided Gill with an op-portunity to contribute to the elusive value ofthe astronomical unit. However, he soon dis-covered firsthand the difficulty of using the tran-sit of Venus to determine solar parallax. Uponmagnification, the image of the planetary disk be-came insufficiently sharp, so it was very difficultfor astronomers to measure the precise momentof first contact, even with Gill’s precisionchronometers. In 1876 Gill departed on friendlyterms from his position as director of LordLindsay’s observatory.

Along with his wife, Gill then conducted hisown privately organized expedition to AscensionIsland in 1877 to measure solar parallax. Thecouple made their arduous journey to this tinyisland in the middle of the South AtlanticOcean just to precisely measure Mars during itsclosest approach to Earth. Gill used the distancefrom the Royal Greenwich Observatory toAscension Island as a baseline. After six monthson Ascension, he was able to obtain reasonableresults, but he was still not satisfied. He also rec-ognized and began to follow JOHANN GOTTFRIED

GALLE’S suggestion to use asteroids with theirpointlike masses in making measurements of so-lar parallax. He knew this was the right approach,because he had already made a preliminary (butnot successful) effort, by observing the asteroidJuno during the Mauritius expedition.

In 1889 Gill organized an international ef-fort that successfully made precise measurementsof the solar parallax by observing the motion ofthree asteroids (Iris, Victoria, and Sappho).From the observations, Gill calculated a valueof the astronomical unit that remained the in-ternational standard for almost a century. Hisvalue of 8.80 arc seconds for solar parallax wasreplaced in 1968 with a value of 8.794 arc sec-

onds obtained by radar observations of solar sys-tem distances. Then, between 1930 and 1931,SIR HAROLD SPENCER JONES followed Gill’s workand used observations of the asteroid Eros tomake refined estimates of solar parallax. After adecade of careful calculation, Jones obtained avalue of 8.790 arc seconds.

The astronomical expeditions of 1874 and1877 brought Gill recognition within the Britishastronomical community, and in 1879 he was ap-pointed as Her Majesty’s Royal Astronomer atthe Cape of Good Hope Observatory in SouthAfrica. He served with great distinction as royalastronomer at this facility until his retirement in1907. Early in this appointment, he accidentallybecame a proponent for astrophotography,when he successfully photographed the greatcomet of 1882 and then noticed the clarity ofthe stars in the background of his comet pho-tographs. He upgraded and improved theobservatory so it could play a major role in pho-tographing the Southern Hemisphere sky insupport of such major international efforts asthe Carte du Ciel project. He collaborated withJACOBUS CORNELIUS KAPTEYN in the creationof the Cape Durchmusterung—an enormous cat-alog published in 1904 that contained more than400,000 Southern Hemisphere stars whose posi-tions and magnitudes were determined fromphotographs taken at the Cape of Good HopeObservatory. Gill was knighted in 1900.

The Gills returned to Great Britain fromSouth Africa in 1907 and retired in London.There, he busied himself by completing a book,History and Description of the Cape Observatory,published in 1913. He died in London on January24, 1914. He was internationally recognized asone of the great observational astronomers of theperiod. He was elected as a fellow of the RoyalAstronomical Society in 1867 and served as thesociety’s president from 1909 to 1911. He receivedthe society’s Gold Medal twice: in 1882 and againin 1908. His numerous other awards included the1900 Bruce Gold Medal from the Astronomical

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Society of the Pacific and the 1899 Watson Medalfrom the U.S. National Academy of Sciences.

5 Goddard, Robert Hutchings(1882–1945)AmericanPhysicist, Rocket Engineer

Robert Goddard was the brilliant, but reclusive,American physicist who promoted rocket sci-ence and cofounded the field of astronautics inthe early part of the 20th century—independentof KONSTANTIN EDUARDOVICH TSIOLKOVSKY

and HERMANN JULIUS OBERTH. However, un-like Tsiolkovsky and Oberth, who were pri-marily theorists, Goddard performed manyhands-on pioneering rocket experiments. Includedin his long list of accomplishments is the suc-cessful launch of the world’s first liquid pro-pellant rocket on March 16, 1926. Goddard’slifelong efforts resulted in more than 214 U.S.patents, almost all rocket-related. Today, Goddardis widely recognized as the father of modernrocketry.

Goddard was born in Worcester, Massa-chusetts, on October 5, 1882, to Nahum DanfordGoddard and Fannie Louise Hoyt Goddard.When Robert was very young, the family movedto Boston, but returned to Worcester in 1898.His father was a machine shop superintendent,and visits to his father’s shop helped nurture hisfascination with gears, levers, and all types ofmechanical gadgets. As a child he was very sicklyand suffered from pulmonary tuberculosis.Forced to avoid strenuous youthful games andsports, Goddard retreated to more cerebral pur-suits like reading, daydreaming, and keeping adetailed personal diary.

In the 1890s he became very interested inspace travel. He was especially influenced byJules Verne’s classic science fiction novel Fromthe Earth to the Moon, and by H. G. Wells’s, TheWar of the Worlds, which appeared as a daily

serial feature in a Boston newspaper. Many yearslater, Robert Goddard sent a personal letter toH. G. Wells, explaining what a career stimulusand source of inspiration that particular storywas to him in his youth. The English authorpenned a letter back to Goddard, acknowledg-ing the kind remarks.

Starting in childhood, Goddard began tokeep a diary in which he meticulously recordedhis thoughts and his experiences—the successesas well as the failures. For example, one day during his early teens, an explosive mixture ofhydrogen and oxygen shattered the windows ofhis improvised home laboratory. Without muchemotion he dutifully noted in his diary: “ . . .such a mixture must be handled with great care.”Later on, his wife would help him carefully doc-ument the results of his rocket experiments.

Goddard’s youthful diary describes a veryspecial event in his life that happened shortlyafter his 17th birthday. On October 19, 1899, heclimbed an old cherry tree in his backyard withthe initial intention of pruning it. But becauseit was such a pleasant autumn day, he remainedup in the tree for hours, thinking about his fu-ture and whether he wanted to devote his life torocketry. His thoughts even wandered to devel-oping a device that could reach Mars. October19 thus became Goddard’s personal holiday orspecial “Anniversary Day”—the day on whichhe committed his life to rocketry and spaceflight. Of that life-changing day, Goddard laterwrote: “I was a different boy when I descendedthe tree from when I ascended, for existence atlast seemed very purposive.”

Because of his frequent absence from schooldue to illness, he did not graduate from highschool until 1904, when he was in his early 20s.At high school graduation, he concluded hisoration with the following words: “It is difficultto say what is impossible, for the dream of yes-terday, is the hope of today, and the reality oftomorrow.” This is Goddard’s most frequentlyremembered quotation.

134 Goddard, Robert Hutchings

Goddard, Robert Hutchings 135

Robert H. Goddard and the world’s first liquid propellant rocket in its launch frame. On March 16, 1926,Goddard successfully flight-tested this historic liquid oxygen-gasoline rocket in a field at Auburn,Massachusetts. From 1930 to 1941 he made substantial progress in the development of larger liquid-propellantrockets. With his pioneering experiments he developed and demonstrated the fundamental principles of modernrocket technology. Along with visionary theoreticians Konstantin Tsiolkovsky and Hermann Oberth, Goddard isregarded as one of the founding fathers of astronautics. (Courtesy of NASA)

136 Goddard, Robert Hutchings

When he became an undergraduate student,most people, including many supposed scientificexperts who should have known better, mistak-enly believed that a rocket could not operate inthe vacuum of space because “it needed an at-mosphere to push on.” Goddard knew better. Heunderstood the theory of reaction engines, andwould later use novel experimental techniquesto demonstrate the fallacy of this common andvery incorrect hypothesis about a rocket’s in-ability to function in outer space. By the timehe died, the large liquid-propellant rocket wasnot only a technical reality, but also was scien-tifically recognized as the technical means forachieving another 20th-century “impossible”dream—interplanetary travel.

Goddard enrolled at Worcester PolytechnicInstitute in 1904. In his freshman year, he wrotea very interesting essay in response to one pro-fessor’s assignment about transportation systemspeople might use far in the future—the profes-sor’s target year was 1950. Goddard’s paper de-scribed a high-speed vacuum tube railway systemthat would take a specially designed commutertrain from New York to Boston in only 10 minutes!His proposed train used electromagnetic levita-tion and accelerated continuously for the firsthalf of the trip and then decelerated continu-ously at the same rate during the second half ofthe trip.

In 1907 he achieved his first public notori-ety as a “rocket man” when he ignited a blackpowder (gunpowder) rocket in the basement ofthe physics building. As clouds of gray smokefilled the building, school officials became im-mediately “interested” in Goddard’s work. Muchto their credit, the tolerant academic officials atWorcester Polytechnic Institute did not expelhim for the incident. Instead, he went on tograduate with his bachelor of science degree in1908 and then remained at the school as an in-structor of physics.

He began graduate studies in physics atClark University in 1908. His enrollment began

a long relationship with the institution, first asa student and later as a faculty member. In 1910he earned his master’s degree and followed it thenext year with his Ph.D. in physics. After re-ceiving his doctorate, he accepted a researchfellowship at Princeton University from 1912to 1913. However, he suffered a near-fatal re-lapse of pulmonary tuberculosis in 1913 that in-capacitated him for many months. Recovered,Goddard joined the faculty at Clark Universitythe following year as an instructor of physics. By1920 he was a full professor of physics and alsothe director of the physical laboratories at Clark.He retained these positions until he retired inAugust 1943.

Clark University provided Goddard withthe small laboratory, supportive environment,and occasional, very modest amount of institu-tional funding necessary to begin serious exper-imentation with rockets. Following his return toClark University, Goddard met his future wife,Esther Christine Kisk. Beginning in 1918, shestarted helping him carefully compile the notesand reports of his many experiments. Over timetheir professional relationship turned personaland they were married on June 21, 1924. Theyhad no children.

Esther Kisk Goddard created a home envi-ronment that provided her husband with a con-tinuous flow of encouragement and support. Shecheered with him when an experiment worked;she was also there to cushion the blow of exper-imental failure or to buffer him from the harshremarks of uninformed detractors. She was thepublicly transparent, but essential, partner in“Goddard, Inc.”—the chronically underfunded,federally ignored, but nevertheless incrediblyproductive husband-wife rocket research teamthat achieved many marvelous engineering mile-stones in liquid propulsion technology in the1920s and 1930s.

As a professor at Clark University, Goddardresponded to his childhood fascination withrockets in a methodical, scientifically rigorous

way. Goddard recognized the rocket as the en-abling technology for space travel and then,unlike Tsiolkovsky and Oberth, he went well be-yond a theoretical investigation of these inter-esting reaction devices. He enthusiasticallydesigned new rockets, invented special equip-ment to analyze their performance, and thenflight-tested his experimental vehicles to trans-form theory into real world action. In 1914Goddard obtained the first two of his numerousrocketry-related U.S. patents. One was for arocket that used liquid fuel; the other for a two-stage, solid fuel rocket.

In 1915 Goddard performed a series of clev-erly designed experiments in his laboratory atClark University that clearly demonstrated arocket engine generates thrust in a vacuum.Goddard’s work provided indisputable experi-mental evidence showing that space travel wasindeed possible. Yet his innovative research wassimply too far ahead of its time. His academiccolleagues generally did not understand or ap-preciate the significance of the rocket experi-ments, and Goddard continued to encountergreat difficulty in gathering any financial supportto continue. Since no one else thought rocketphysics was promising, he became disheartenedand even thought very seriously about aban-doning his lifelong quest.

But somehow Goddard persevered and inSeptember 1916 sent a description of his exper-iments along with a modest request for fundingto the Smithsonian Institution. Upon reviewingGoddard’s proposal, officials at the Smithsonianfound his rocket experiments to be “sound andingenious.” One key point in Goddard’s favorwas his well-expressed desire to develop the liquid-propellant rocket as a means of taking in-struments into the high-altitude regions ofEarth’s atmosphere—regions that were well be-yond the reach of weather balloons. This earlymarriage between rocketry and meteorologyproved very important, because this relationshipprovided officials in private funding institutions

a tangible reason for supporting Goddard’s pro-posed rocket work.

On January 5, 1917, the Smithsonian Institut-ion informed Goddard that he would receive a$5,000 grant from the institution’s HodgkinsFund for atmospheric research. Not only did theSmithsonian provide additional funding toGoddard over the years, but equally important,it published Goddard’s two classic monographson rocket propulsion: the first in 1919 and thesecond in 1936.

In 1919 Goddard summarized his early rockettheory work in the classic report “A Method ofReaching Extreme Altitudes.” It appeared involume 71, number two of the SmithsonianMiscellaneous Collections in late 1919 and then as“Smithsonian Monograph Report Number 2540”in January 1920. This was the first Americanscientific work that carefully discussed all thefundamental principles of rocket propulsion.Goddard described the results of his experimentswith solid-propellant rockets and even includeda final chapter on how the rocket might be usedto get a modest payload to the Moon. He sug-gested carrying a payload of explosive powder thatwould flash upon impact and signal observers onEarth. Unfortunately, nontechnical newspaper re-porters missed the true significance of this greattreatise on rocket propulsion and decided insteadto sensationalize his suggestion about reachingthe Moon with a rocket. The press gave him suchunflattering nicknames as “Moony” and the“Moon man.” The headline of the January 12,1920, edition of the New York Times boldly pro-claimed “Believes Rocket Can Reach Moon,” andthe accompanying article proceeded to soundlycriticize Goddard for not realizing that a rocketcannot operate in a vacuum. Goddard became anewspaper sensation, but his newfound fame wasall derogatory.

Offended by such uninformed adverse pub-licity, Goddard chose to work in seclusion for therest of his life. He avoided further controversy bypublishing as little as possible and refusing to

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138 Goddard, Robert Hutchings

grant interviews to the press. These actionscaused much of his brilliant work in rocketry togo unrecognized during his lifetime. The Germanrocket scientists from Peenemünde, who emi-grated to the United States after World War II,expressed amazement at the extent of Goddard’sinventions, many of which they had painfully du-plicated. They also wondered aloud why the U.S.government had chosen to totally ignore thisbrilliant man.

Independent of Tsiolkovsky and Oberth,Goddard recognized that the liquid-propellantrocket was the key to interplanetary travel. Hethen devoted his professional life to inventingand improving liquid-propellant rocket technol-ogy. Some of his most important contributionsto rocket science are briefly summarized below.

In 1912 Goddard first explored on a theo-retical and mathematical basis the practicalityof using the rocket to reach high altitudes andeven attain a sufficiently high velocity (calledthe escape velocity) to leave Earth and get tothe Moon. He obtained patents in 1914 for theliquid-propellant rocket and for the concept ofa two-stage rocket.

In 1915 he used a clever static test experi-ment in a vacuum chamber to show that therocket would indeed function in outer space. AsWorld War I drew to a close, Goddard demon-strated several rockets to U.S. military officials,including the prototype for the famous bazookarocket used in World War II. However, withWorld War I almost over, the U.S. governmentsimply chose to ignore Goddard and the valueof his rocket research.

Undiscouraged by a lack of government in-terest, he turned his creative energy on the de-velopment of the liquid-propellant rocket andperformed a series of important experiments atClark University between 1921 and 1926. Onetest is particularly noteworthy. On December 6,1925, Goddard performed a successful captive(that is, a static, or nonflying) test of a liquid-fueled rocket in the annex of the physics build-

ing. During this test, Goddard’s rocket generatedenough thrust to lift its own weight. Encouragedby the static test, Goddard proceeded to constructand flight-test the world’s first liquid-fueledrocket.

On March 26, 1926, Goddard made spacetechnology history by successfully launching theworld’s first liquid-propellant rocket. Eventhough this rocket was quite primitive, it isnonetheless the technical ancestor of all mod-ern liquid-propellant rockets. The rocket engineitself was just 1.2 meters tall and 15.2 centime-ters in diameter. Gasoline and liquid oxygenserved as its propellants. Only four people wit-nessed this great historic event. The publicity-shy physicist took just his wife and two loyal staffmembers from Clark University (P. M. Roopeand Henry Sachs) to a snow-covered field atEffie Ward’s farm in Auburn, Massachusetts.“Auntie Effie,” as he referred to her in his diary,was a distant relative.

Goddard assembled a metal frame structurethat resembled a child’s jungle gym to supportthe rocket prior to launch. His wife served as theteam’s official photographer. The launch proce-dure was quite simple, since there was no count-down: Goddard carefully opened the fuel valves,then, with the aid of a long pole, Sachs applieda blowtorch to ignite the engine. With a greatroar, the tiny rocket vehicle jumped from themetal support structure, flew in an arc, and thenlanded unceremoniously some 56 meters away ina frozen cabbage patch. In all, this historic rocketrose to a height of about 12 meters and its en-gine burned for only two and one-half seconds.Despite its great technical significance, theworld would not learn about Goddard’s greatachievement for some time.

With modest funding from the Smithsonian,Goddard continued his work. In July 1929 helaunched a larger and louder rocket nearWorcester that successfully carried an instru-ment payload (a barometer and a camera)—thefirst rocket to do so. However, it also created a

major disturbance. As a consequence the localauthorities ordered him to cease his rocket flightexperiments in Massachusetts.

Fortunately, the aviation pioneer CharlesLindbergh (1902–74) became interested inGoddard’s work and helped him secure addi-tional funding from the philanthropist DanielGuggenheim. A timely grant of $50,000 allowedGoddard to set up a rocket test station in a re-mote part of the New Mexico desert, nearRoswell. There, undisturbed and well out of thepublic view, Goddard conducted a series of im-portant liquid-propellant rocket experiments inthe 1930s. These experiments led to Goddard’ssecond important Smithsonian monograph,“Liquid-Propellant Rocket Development,” whichwas published in 1936. On March 26, 1937,Goddard launched a liquid-propellant rocketnicknamed “Nell” that flew for 22.3 seconds andreached a maximum altitude of about 2.7 kilo-meters. This was the highest altitude ever ob-tained by one of Goddard’s rockets.

Goddard retained only a small technical staffto assist him in New Mexico and avoided con-tact with the rest of the scientific community.Yet, his secretive, reclusive nature did not impairthe innovative quality of his work. In 1932 hepioneered the use of vanes in the rocket engine’sexhaust with a gyroscopic control device to helpguide a rocket during flight. In 1935, he becamethe first person to launch a liquid-propellantrocket that attained a velocity greater than thespeed of sound. Finally, in 1937, Goddard suc-cessfully launched a liquid-propellant rocket thathad its motor pivoted on gimbals so it could re-spond to the guidance signals from its onboardgyroscopic control mechanism. He also pio-neered the use of the converging-diverging (deLaval) nozzle in rocketry, tested the first pulse jetengine, constructed the first turbopumps for use

in a liquid-propellant rocket, and developed thefirst liquid-propellant rocket cluster.

In his lifetime he registered 214 patents onvarious rockets and their components. Unfortu-nately, since his pioneering rocket work wentessentially ignored, he finally closed his rocketfacility near Roswell and moved to Annapolis,Maryland. There he worked with the U.S. Navyto provide his rocket technology expertise in theuse of solid-propellant rockets to assist seaplanetakeoff. As a lifelong solitary researcher, Goddardfound the social demands of team-developingjet-assisted takeoff (JATO) for the governmentnot particularly to his liking.

Just before his death, he was able to inspectthe twisted remains of a German V-2 rocket thathad fallen into U.S. hands and been taken backto the United States for analysis. As he per-formed a technical autopsy on the rocket, a mil-itary intelligence analyst inquired: “Dr. Goddard,isn’t this just like your rockets?” Without show-ing any emotion, Goddard calmly replied: “Seemsto be.”

America’s visionary “rocket man” died ofthroat cancer on August 10, 1945, in Annapolis,Maryland, and did not see the dawn of the spaceage. In 1951 Mrs. Esther Goddard and theGuggenheim Foundation, which helped fundmuch of Goddard’s rocket research, filed a jointlawsuit against the U.S. government for in-fringement on his patents. In 1960 the gov-ernment settled this lawsuit and in the processofficially acknowledged Goddard’s great contri-butions to modern rocketry. That June, theNational Aeronautics and Space Administration(NASA) and the Department of Defense jointlyawarded his estate the sum of $1 million for theuse of his patents. NASA’s Goddard Space FlightCenter in Greenbelt, Maryland, now honors hismemory by carrying his name.

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140

H5 Hale, George Ellery

(1868–1938)AmericanAstrophysicist

George Ellery Hale was born on June 29, 1868,in Chicago, Illinois. Because his mother, Mary,had lost two previous children in infancy, he wascoddled as a child by ever-attentive nurses andteachers, as were two subsequent Hale children,Martha and William. Hale’s father, William E.Hale, was a young struggling engineer-salesmanfor a company in nearby Beloit, Wisconsin, wholater amassed a fortune in the emerging elevatorbusiness, which thrived as the city was rebuiltafter the Great Chicago Fire of 1871. This fam-ily fortune was to have a crucial influence onthe course of Hale’s scientific life.

Early on, Hale became fascinated with themicroscope. As he examined everything aroundhim in great detail, taking copious notes, hisfather bought more and more powerful instru-ments. In his early teens he came upon a de-scription of the spectrum, as seen as a rainbowof light through a prism, and became fascinatedby the notion of determining physical proper-ties of the known universe by correspondingspectroscopic analysis.

Hale’s biographical notebooks indicate thathe built his first telescope at the age of 13, but

it was small and the images unclear. When helearned of the availability of a four-inch Clarkrefractor, his father bought it for him. Hale in-stalled the telescope on the roof of the house,and after he observed Saturn, Jupiter, and theMoon for the first time, was inspired to pursueresearch in the field of astronomy. Soon after, heattached a plateholder to the telescope andobserved a partial eclipse of the Sun, markingthe beginning of a lifelong passion of observingsunspots.

With the continuing encouragement of hismother to pursue intellectual endeavors and sat-isfy his inquisitive nature, Hale became educatedin the arts, literature, and music. Perhaps moreimportant, Hale had his father’s wholeheartedfinancial support, which allowed him to accu-mulate gratings, lenses, telescopes, and otherinstrumentation as he built a sophisticated plan-etarium in the family backyard. By the time hewas 17, Hale had met prominent astronomers inthe Chicago area and had made observations atthe Dearborn Observatory in nearby DouglasPark.

Such was Hale’s scientific precocity thatwhen he ordered a small diffraction grating fromthe famous instrument maker J. A. Brashear,Brashear was astounded to find Hale was only17 years old when he finally met him after cor-responding from his manufacturing facility in

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Pittsburgh. Brashear had surmised during theircorrespondence that Hale was a mature and ex-perienced astronomer.

Hale’s college years were eventful indeed.He entered Massachusetts Institute of Techno-logy (MIT) in 1886 and pursued a degree inphysics. Since MIT at the time did not offercourses in astronomy, Hale wrote to the notedprofessor EDWARD CHARLES PICKERING, direc-tor of the Harvard College Observatory, offer-ing his services as a volunteer assistant.Pickering, who was breaking new ground in as-tronomical photography and stellar spectralclassification, was so impressed with the youngHale’s knowledge of spectroscopy as it could beapplied to astronomy that he hired Hale andkept him employed as an assistant for almostthree years.

While a junior in college, and initiallyagainst his family’s wishes, Hale became engagedto a Brooklyn girl, Evelina Conklin, whom hehad met on a family summer vacation when hewas 13. This event was followed by the publica-tion of his first article, an essay describing theevolution of the spectroscope and its applica-tions to astronomy. Also while a junior, he in-vented the spectroheliograph, a device thatmade it possible to observe the Sun’s promi-nences and sunspots in daylight. He tested theinstrument with Pickering at the HarvardObservatory, and the invention made him worldfamous by the time he graduated from MIT in1890 with his degree in physics.

On their honeymoon in 1890, the Hales vis-ited the Lick Observatory on Mount Hamilton,near San Jose, California. There, Hale had achance to observe through Lick’s 36-inch re-fractor, then the largest in the world, and wasoffered the opportunity to work on the large tel-escope with his spectroheliograph. But by nowHale was receiving job offers from all over theworld, and he declined the Lick position afterbeing warned by colleagues that daytime obser-vations on Mount Hamilton were difficult due

to air turbulence caused by warming of the lo-cal terrain.

The Hales returned to Chicago, where Halecontinued to build his own observatory with a12-inch refractor his father bought him. Hecalled it the Kenwood Physical Observatory, andas he worked there the huge 36-inch Lick tele-scope was always on his mind. During this time,when he was only 22, Hale was elected a Fellowof the British Royal Astronomical Society. Soonafter, he was offered a position at the prestigiousUniversity of Chicago, but when he discoveredthat the president of the university really cov-eted his Kenwood telescope and instruments—and possibly was interested in a generous en-dowment by his father—Hale decided to travelto Europe instead.

In Europe, Hale met virtually every famousastronomer and astrophysicist and visited all thescientific institutions and laboratories he could.Back in the United States, Hale proposed anddeveloped a scientific journal that would even-tually become the esteemed Astrophysical Journal.In 1892 he again was offered a position in theUniversity of Chicago’s new physics department,which he accepted due to the fact that he couldthen work with the eminent professor ALBERT

ABRAHAM MICHELSON (who would become theuniversity’s first Nobel laureate in 1908). Halewas named associate professor of astrophysics,the first astronomer in the world to hold such atitle. Now came the work that would defineHale’s position forever in the field of astronomy:his successive role in the creation of the world’sthree greatest observatories.

While at the University of Chicago, Halebecame aware of the availability of two 42-inchglass discs and decided to devote his energiesinto creating a world-class observatory at theuniversity. However, he needed even moremoney than his father had, so Hale persuadeda local millionaire, Charles Tyson Yerkes, tohelp fund the effort. When all was said anddone, Hale found himself director of the Yerkes

142 Hall, Asaph

Observatory at Williams Bay, Wisconsin, boast-ing a 40-inch refractor telescope, the largest as-trophysical laboratory in the world. Hale was 24years old.

Political strife and ego-driven financialarguments between Yerkes Observatory direc-tors and the benefactors convinced Hale tomove his family to California in 1904. There,on Mount Wilson, near Pasadena, Hale set up asmall laboratory to continue his sunspot obser-vations, and received a grant from the CarnegieInstitution to form the Mount Wilson SolarObservatory, which would eventually house a100-inch telescope, the largest in the world.The Mount Wilson Observatory under Hale’sdirection transformed the field of astrophysics.Here, galaxies were explained, EDWIN POWELL

HUBBLE discovered the expanding universe, andthe phenomena of sunspots and solar magnet-ism were analyzed. Also while at Mount Wilson,Hale played a major role in transforming theThroop Polytechnic Institute into the world-acclaimed California Institute of Technology(Caltech).

Although he never lived to see his finalproject realized, Hale also set in motion the ef-forts to persuade the Rockefeller Foundation tofund a 200-inch telescope, the largest ever built,at Mount Palomar, affiliated with Caltech.Completed in 1948, 10 years after his death, itwas named the Hale Telescope.

Hale wrote three books: Depths of theUniverse (1924), Beyond the Milky Way (1026),and Signals from the Stars (1931). He receivedevery major scientific medal and award and wasan esteemed member of every major scientificsociety of his time. He coined the word astro-physics, and his invention of the spectrohelio-graph ushered in the age of solar prominence andsunspot observation. He created the three mostfamous observatories of the 20th century, and heleft the scientific community with what is to thisday the world’s leading research journal in thefield of astrophysics.

Hale died of cardiac failure due to arterialsclerosis on February 21, 1938, in Pasadena, afew months short of his 70th birthday.

5 Hall, Asaph(1829–1907)AmericanAstronomer

In 1877, while he was a staff member at the U.S.Naval Observatory in Washington, D.C., AsaphHall discovered the two small moons of Mars.He called the larger innermost moon Phobos(“fear”), and the smaller outermost moonDeimos (“terrified flight”)—after the attendantsof Mars, the god of war in Roman mythology(known as Ares in Greek mythology).

The American astronomer Hall was born inGoshen, Connecticut, on October 15, 1829. Hisfather died when he was just 13 years old, so hehad to leave school to support his family as acarpenter’s apprentice. In the early 1850s, Halland his wife, Angelina, were working as school-teachers in Ohio, when he decided to become aprofessional astronomer. Since the difficult daysof his childhood, he had always entertained adeep interest in astronomy and taught himselfthe subject as best he could. So in 1857, withonly a little formal training (approximately oneyear) at the University of Michigan and a gooddeal of encouragement from his wife, he ap-proached William Bond (1789–1859), the di-rector of the Harvard College Observatory, for aposition as an assistant astronomer. Recalling hisown struggle to become an astronomer, Bond ad-mired Hall’s spunk and hired him as an assistantresearcher to support his son, George PhillipsBond (1825–65), who also worked at the obser-vatory. Hall’s starting salary was just three dollarsa week, but that did not deter him from pursu-ing his dream.

His experience at the Harvard CollegeObservatory polished Hall’s skills as a professional

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astronomer. By 1863 he had joined the U.S.Naval Observatory in Washington, D.C., and heeventually took charge of its new 26-inchrefractor telescope. During this period, the ob-servatory and its instruments were under the di-rection of SIMON NEWCOMB, who was actuallymore interested in the mathematical aspects ofastronomy than in performing personal observa-tions of the heavens.

In December 1876 Hall was observing themoons of Saturn when he noticed a white spoton the generally featureless, butterscotch-col-ored globe of the ringed planet. He carefully ob-served this spot and used it to estimate the rateof Saturn’s rotation to considerable accuracy.Hall worked out the period of rotation to beabout 10.23 hours—a value comparable to thevalue reported by SIR WILLIAM HERSCHEL in1794. The contemporary value for the period ofrotation of Saturn’s equatorial region is approx-imately 10.66 hours.

In summer 1877 Mars was in oppositionand approached within 56 million kilometersof Earth. Hall pondered whether the RedPlanet had any natural satellites. Other as-tronomers had previously searched for Martianmoons and were unsuccessful. However, curi-ously, the writer Jonathan Swift mentioned twoMartian satellites in his famous 1726 novel,Gulliver’s Travels. On the night of August 10,1877, Hall made his first attempt with the pow-erful Naval Observatory telescope, but viewingconditions along the Potomac River were hor-rible and Mars produced a glare in the telescopethat made searching for any satellites very dif-ficult. He returned home very frustrated, buthis wife encouraged him to keep trying. On thefollowing evening, Hall detected a suspiciousobject near the planet just before fog rolled infrom the Potomac River and enveloped theNaval Observatory. It was not until the eveningof August 16 that Hall again observed a faintstarlike object near Mars, which proved to beits tiny outermost moon, Deimos. He showed

the interesting object to an assistant and in-structed him to keep quiet about the discovery.Hall wanted to confirm his observations beforeother astronomers could take credit for his find-ing. On the evening of August 17, as Hallwaited for Deimos to reappear in the telescope,he suddenly observed the larger, inner moon ofMars, which he called Phobos. By August 18,Hall’s excitement and log notes had informallyleaked news of his discovery to the other as-tronomers at the Naval Observatory. Thatevening the observatory was packed with ea-ger individuals, including Newcomb, each try-ing to snatch a piece of the “astronomicalglory” resulting from Hall’s great discovery. Forexample, Newcomb improperly implied in asubsequent newspaper story that his calcula-tions helped Hall realize that the two newobjects were satellites orbiting Mars. This at-tempt at “sharing” Hall’s discovery caused agreat deal of personal friction between the twoastronomers that lasted for decades. ImitatingHall’s work, astronomers at other observatoriessoon claimed they had discovered a third andfourth moon of Mars—hasty “discoveries” thatnot only proved incorrect but were based onproclaimed orbital motion data violatingKepler’s laws.

When the dust settled, astronomers aroundthe world confirmed that Mars possessed just twotiny moons, and Hall received full and sole creditfor the discovery. The Royal AstronomicalSociety in London awarded him its prestigiousGold Medal in 1877.

Hall remained at the Naval Observatoryuntil his retirement in 1891. He focused his at-tentions on planetary astronomy, determiningstellar parallax, and investigating the orbital me-chanics of binary star systems, such as the visualbinary 61 Cygnus. Following retirement from theNaval Observatory, Hall became a professor ofastronomy at Harvard from 1896 to 1901. Hedied in Annapolis, Maryland, on November 22,1907.

144 Halley, Sir Edmund

5 Halley, Sir Edmund(ca. 1656–1742)EnglishAstronomer, Mathematician, Physicist

Edmund Halley was born in Haggerston,England, around October 29, 1656, a date thatis approximate, although somewhat based on theyear Halley claims he was born, due to a changein the calendar system around that time. His fa-ther, also named Edmund Halley, was a wealthysoap maker and landlord, which afforded his sonmany privileges in his early youth. When Halleywas 10 years old, the Great London Fire of 1666ravaged the family’s business, but not com-pletely. The shrewd businessman managed his fi-nances well enough to provide private tutoringfor his son and then enroll him in the presti-gious St. Paul’s School, where young Halley ex-celled in mathematics, began his fascinationwith instrumentation, and started on his lifelongpath of studying the night sky.

When Halley entered Queen’s College atOxford in 1673, at 17 years old, he was alreadyan accomplished astronomer. With an extensiveset of instruments given to him as a gift from hisfather, and the knowledge to use them, Halleyeasily caught the attention of John Flamsteed(1646–1719), the Astronomer Royal, who wasworking both at Oxford and at the GreenwichObservatory. By 1675 Halley had become his as-sistant. One of Halley’s observations at Oxfordwas an occultation, the concealing of one heav-enly body by another, as for example of a star bya planet. He noted the occultation of Mars bythe Moon on August 21, 1676, and featured thisin his first published article in the journalPhilosophical Transactions of the Royal Society.

The next significant event in Halley’s lifeseems to be his travel in 1676, when he leftOxford to go on a voyage to the island of St.Helena, off the African coast, the southernmostterritory under British rule. His dream, literally,was to construct an observatory to chart the

southern skies, and he convinced the powerswho could make this happen that it would com-plement the Greenwich Observatory’s work inthe northern skies. This venture was financiallysupported by his father and by influential RoyalSociety members. King Charles II also got in-volved, personally requesting the East IndiaCompany to transport Halley and a colleague.During the trip, Halley redesigned a sextantand made notes of oceanic and atmosphericphenomena.

Halley was on St. Helena for 18 months, andhe made the first complete observation of a tran-sit of Mercury, catalogued 341 SouthernHemisphere stars in his Catalogus stellarum aus-tralium, and discovered the star cluster inCentaurus—all of which he published upon hisreturn to the Royal Society in 1678. This workmade him a reputable astronomer, but Halley of-ficially had no degree. Since he had left Oxfordwithout graduating, which was very common forwealthy students, in 1678 he was granted anhonorary degree from Oxford by edict of KingCharles II. That same year he was made a mem-ber of the Royal Society, at the age of 22 one ofits youngest Fellows.

In 1680 Halley decided to travel throughEurope with a friend from school. En route, nearCalais, he observed a comet. With his interestsparked, he continued his trip to Paris, where hemet up with fellow astronomer GIOVANNI

DOMENICO CASSINI and the two observed thecomet together.

In 1681 he married Mary Tooke. The fol-lowing year he decided to visit SIR ISAAC

NEWTON in Cambridge for some professional ca-maraderie. Halley had been working on a proofof planets having elliptical orbits, and much tohis amazement, Newton had already provedthe thesis. Even more astonishing, he had no in-tention of publishing his proof. Halley thenurged Newton to compose his epic PrincipiaMathematica, and even financed its publication,eventually earning back his investment when

Halley, Sir Edmund 145

the work sold extremely well. Halley edited thework and volunteered to write an introduction,“Ode to Newton,” which heaped great praiseon Newton and his scientific brilliance. Famousdiscoveries resulted for both men out of thisventure. Newton discovered gravity, and Halleydiscovered Newton.

In 1684 Halley’s father, who had remarriedin 1681 after being a widower for 10 years, dis-appeared. After a five-week absence, his bodywas found, the victim of a murder. In addition tothe great emotional loss, it was a sudden end toHalley’s lifelong funding from his father, whowas a dedicated patron of his son’s work at therate of a £300 annual allowance. By 1685 Halleywas working for the Royal Society as, amongother things, editor of their publication Philo-sophical Transactions, a position he held until1696.

Halley’s vast interest in a variety of fields ledhim to make contributions in other areas of sci-ence over the next few years. By 1686 he hadcompleted a new map of the world, in which heshowed the prevailing winds over the oceans.This new work on trade winds and the tides wasa great contribution to science, and ultimatelyearned him credit as the founder of geophysics.

By 1691, however, Halley felt ready to getback into academia, and he decided to pursueappointment to an astronomy chair at Oxford.Halley could have reasonably expected somesupport from his old friend and mentorFlamsteed, from his days at Oxford and theGreenwich Observatory. But Flamsteed dislikedNewton, who owed his great success to Halley,and while it is fair to say that many people per-sonally disliked Newton, it seemed not enoughreason to abandon Halley in his quest for a job.So Flamsteed created other reasons. From a sci-entific perspective, Flamsteed was upset forwhat he perceived as a slap at the observatoryby Newton, thinking that the Royal Observa-tory should have received more credit regardingNewton’s theories. But his most convincing

diatribe, it turned out, was that Flamsteed con-sidered Halley a bad Christian because Halleyallegedly did not believe solely in the biblicalrendition of creation. The common theme inastronomy of science versus religion reared itsugly head. Flamsteed told the university that hethought Halley would “corrupt” the students,and Halley did not get the job.

Unperturbed, Halley continued his researchand work for the Royal Society. In 1693 he pub-lished another first, this time a study of mortal-ity rates related to age that was researched fromdocuments in Breslau, Germany. This ultimatelybecame the basis for future actuarial tables usedby insurance companies, and made Halley a pi-oneer in yet another new field of science, socialstatistics.

Newton had become warden of the RoyalMint in 1696, and quickly appointed Halley asdeputy controller of the mint in Chester,England. Halley left the position in 1698 whenKing William III awarded him the command ofa warship, the Paramore Pink, built specificallyfor scientific expeditions. Halley had beenworking on the determination of longitude us-ing a specially designed compass, and the pur-pose of the voyage of the Paramore Pink was totest his new method and discover “new lands”south of the equator.

As a naval captain, Halley started the three-year stint a little shaky. His first voyage in 1698was aborted when he reached Barbados, and hereturned to Portsmouth. A second voyage, in1699, charted the North American coast of theAtlantic, after which he published the firstcharts of equal lines of declination. Several othervoyages along the coasts of England followed. In1702 he spent a year inspecting a naval base andother ports in the Austrian Empire at the requestof Queen Anne.

In 1704, waving goodbye forever to hisoceanic duties, Halley finally made his goal ofteaching at Oxford a reality. He was appointedto the chair of geometry at Oxford as Savilian

146 Hawking, Sir Stephen William

professor, a seat he held for the rest of his life.Flamsteed was not happy about this new ap-pointment, apparently feeling that Halley’s timeat sea had turned him into an even morewretched creature than ever, complaining thatHalley now “talks, swears and drinks brandy likea sea captain.” Halley gave an impressive inau-gural speech, including “an account of the mostcelebrated of the ancient and modern geometri-cians.” And whether for the sake of his friendNewton, or just for the fun of irritatingFlamsteed, Halley confidently “gave his greatestencomiums [to] . . . Mr. Newton.”

It was about this time that Halley started tofocus his interest on comets. Newton had pro-posed that comets had parabolic orbits, butHalley suspected they might in fact be elliptical.Using his own theory, he calculated that the or-bit of the Comet of 1682 was in fact periodic,and was the same comet that had appeared in1531 and 1607. In 1705 Halley predicted thatthe comet would reappear in a pattern of 76years. Halley would not live to see the comet re-turn in December 1758, but when it did it wasimmediately dubbed “Halley’s comet” and, ofcourse, reappeared in 1836, 1910, and 1986;every 76 years since, precisely as predicted.

In 1710 Halley proposed that stars had theirown motions and proved his theory by calculat-ing the motions of three specific stars. The the-ory of proper stellar motion, although new to theWestern world thanks to Halley’s research andcalculations, had been originally proposed by theBuddhist monk and astronomer Zhang Sui(683–727). Halley probably had no knowledgewhatsoever of Sui’s theory. This same year, mostlikely for his work on this theory, Halley wasagain awarded an honorary degree, an M.A.,from Oxford.

Halley continued his work in astronomy inconjunction with his position in geometry atOxford. He also served as an arbiter of severaldisputes. Most famously, he “resolved” Newton’sdispute with Leibniz over who invented the cal-

culus: Newton “won,” although the dispute wasnever really settled during their lifetime.

Over the years Halley was also in and outof disputes and controversies with his old men-tor-turned-critic, Flamsteed. Halley had the lastlaugh when he was appointed Royal Astronomerat Greenwich in 1720, succeeding Flamsteedafter the latter’s death. He held this post for 21years, until age 85, and during this time he in-vented the use of a transit to make lunar obser-vations to determine longitude at sea andcompleted an 18-year observation of the Moon.

In 1729 Queen Caroline wanted to makecertain that England’s beloved scientist Halleywas financially secure. She decreed that Halleyshould be given an additional salary equal tohalf-pay of a naval captain—an amount he con-tinued to receive until his death.

Halley’s scientific and astronomical bril-liance, as well as his aptitude for mathematicallogic, gave the world knowledge that hasaffected even today the important fields of nav-igation, geophysics, meteorology, astronomy,cartography, ballistics, and the development ofmeasurement instruments such as the ther-mometer, the backstaff, and the diving bell.

This preeminent scientist was a member ofthe Royal Society from 1678 to 1743, and of theAcadémie des Sciences at Paris from 1729 untilhis death. His contributions have earned himboth a lunar and a Martian crater named in hishonor. Halley died in Cambridge on January 14,1742.

5 Hawking, Sir Stephen William(1942– )EnglishCosmologist, Physicist

There are few disciplines in which the word ge-nius is used to describe several of its members—physics is one of them. The most renowned ge-nius of the late 20th and early 21st centuries is

Hawking, Sir Stephen William 147

the Lucasian Professor of Mathematics atCambridge, Stephen Hawking—the man whobrought the mind-boggling principles of cos-mology into the everyday realm of the averageperson, and who helped popularize and main-stream such science-fiction ideas as black holes,worm holes, time travel, and life elsewhere inthe universe. Hawking is known as the scientistwho explains to the masses the laws that governthe universe.

Born on January 8, 1942, in Oxford,England, Hawking is fond of saying that hisbirth date was the 300th anniversary of GALILEO

GALILEI’s death. This takes a bit of explaining.One of the legends in astronomy since the late18th century has been that Galileo and SIR

ISAAC NEWTON shared a date in their life—Newton was born the same day that Galileodied, and that day happened to be ChristmasDay, 1642. More than 100 years later, in 1752,the calendar system was changed in England,and the Gregorian calendar was adopted. Goingback in time, after the implementation of theGregorian calendar, and updating the dates ofthe events that happened previous to the in-stallation of this new system has the effect ofchanging the date that Newton was born andthat Galileo died. The date, while they werealive, was December 25, 1642—although eventhis is in question! Some historians site Galileo’sdeath in December 1641, so the new date wouldthen be January 1642; and some say that Newtonwas born in December 1642, so the correctedyear would be January 1643. In any event, if thedates are changed to the Gregorian system andcorrected for today’s time, December 25 becomesJanuary 8, as it relates to our calendar. So, inessence, Hawking was born the same day Galileodied and the same day Newton was born.Perhaps all of this confusion is simply forewarn-ing from the universe that if the time of his birthis confusing, it is nothing compared to thephilosophies and theories he proposes. Yet thisbrilliant man has managed to make even the

most complex subjects of space accessible to theworld at large.

As a young boy, Hawking knew by age 14that mathematics was his life’s calling. He at-tended St. Albans School starting at age 11;then, at age 17, he went to University Collegein Oxford, his father’s alma mater, where he tookup physics because mathematics was not offered.He was notorious for missing classes and labs, atrait he shared with another great physicist,ALBERT EINSTEIN, whose work would play an im-portant role in Hawking’s future career. But un-like Einstein, who barely passed his exams,Hawking graduated at the top of his class with-out much effort. With his undergraduate degreein natural science behind him, Hawking leftOxford and went to Cambridge for his Ph.D. incosmology—a new and relatively unexploredfield.

But something was not quite right withHawking—minor clumsiness escalated intofalling over for no reason, and pretty soon hewas having trouble tying his shoes. WhenHawking went home for Christmas vacation, hisfather, a doctor, noticed the symptoms and tookhim to a specialist, where multiple sclerosis wasruled out. But within a few weeks, Hawking wasdiagnosed with amyotrophic lateral sclerosis(ALS—also called Lou Gehrig’s disease), a de-generative motor neuron disease that causes thebody’s muscles to atrophy. Hawking admits thatthe shock of finding out he had an incurable dis-ease was compounded by the fact that it wasprobably going to kill him before he finished hisPh.D., but when he witnessed the agonizingdeath of a boy with leukemia in the hospital bedacross from him, he gained new insight, realiz-ing that “Clearly, there were people who wereworse off than me.”

The young boy’s death, and the ensuingdreams Hawking had, helped change Hawking’sperspective, and he realized that he needed todo something good with the life he had left. Hestated to enjoy “life in the present,” and he felt

148 Hawking, Sir Stephen William

a surge of hope and purpose. Shortly after his di-agnosis, he resumed his research at Cambridge,earned a research fellowship at Caius College inCambridge, and married an undergraduate atWestfield College in London named Jane Wilde.

Hawking’s chosen field, theoretical physics,proved to be a blessing as his disease continuedto take its toll on his body. He found that theworse his condition became, the more he couldfocus his time on research, rather than lectur-ing. He continued to research and live a rela-tively normal life until 1974, when he lost theability to feed himself or manage the usual ritu-als associated with going to bed. By this time heand his wife had three children, and it was clearthat she could not continue to take care of himalone, so they came up with the brilliant solu-tion of giving a research student free board andpersonal access to Hawking in exchange forhelp. This lasted for six years, until 1980, whenthey brought in professional help and Hawkingeventually needed round-the-clock medicalassistance.

In the early 1980s Hawking’s speech becameslurred, and his lectures required the assistanceof a close friend who could still understand himto “translate” for the audience. Then, in 1985,Hawking came down with pneumonia. After atracheotomy to save his life, his speaking ca-pacity was destroyed. The only way he couldcommunicate was by “raising [his] eyebrowswhen someone pointed to the right letter on aspelling card,” which made it nearly impossibleto get the ideas out of his head and onto paper.

A California computer whiz named WaltWoltosz came to Hawking’s rescue with a pro-gram he wrote in which Hawking could chosewords from a computer screen with a click of aswitch. Soon, Hawking had a computer on hiswheelchair, and a voice synthesizer. The hard-ware and software combination suddenly gavehim the freedom to write at a rate of up to 15words a minute, save his compositions to thecomputer and print them out, or even have the

computer speak for him. It is by this method ofwriting, 15 words a minute, that Hawking hascreated extensive papers on complicated theo-ries, written two books that have sold in themainstream market with international appeal,and lectured around the world. The only prob-lem, Hawking says, is that he now speaks withan American accent.

The beginning of Hawking’s development ofhis popular theories started at Cambridge whenhe met the brilliant mathematician RogerPenrose, whose work on what happens at theend of a star’s life inspired Hawking to devotehimself to the subject of collapsed stars. By 1970the mathematician-and-cosmologist team in-formed the world that they had discovered thatthe universe had a definite beginning of time,about 15 billion years ago in the big bang—confirming the idea originally proposed byRALPH ASHER ALPHER.

The idea of a beginning of time was a con-cept that had been argued on the basis of reli-gion or philosophy for centuries. Hawking wrote,“SIR ARTHUR EDDINGTON once said, ‘Don’tworry if your theory doesn’t agree with the ob-servations, because they are probably wrong.’But if your theory disagrees with the Second Lawof Thermodynamics (in which disorder increaseswith time), it is in bad trouble.”

Hawking and Penrose proved that Einstein’sgeneral theory of relativity supported their the-ories—that when a star collapsed it became ablack hole, a place where “time came to an end,”and that “the expansion of the universe is likethe time reverse of the collapse of a star.” Theycited the uncertainty principle of quantum me-chanics that states an object cannot have botha well-defined position and a well-defined speed,and used the debunked steady state theory (asgalaxies move apart, new galaxies are formed inbetween them from new matter that is con-stantly being formed) for further proof.

By combining the uncertainty principlewith the general theory of relativity, Hawking

Hawking, Sir Stephen William 149

created a new theory, the quantum theory, in-troducing the concept of “imaginary time,”which when combined with three-dimensionalspace forms “a Euclidean space-time,” wherespace and time are “like the surface of theEarth”—with no boundaries. Using the laws ofphysics, the state of the universe can be calcu-lated in imaginary time, and therefore can alsobe calculated in real time, and so the beginningof time can be pinpointed.

In 1992, when the satellite COBE (CosmicBackground Explorer) found “irregularities in themicrowave background radiation,” Hawkingsays, “we saw back to the origin of the universe.”The work Hawking and Penrose started morethan two decades prior suddenly had some ob-servational teeth, although even Hawkingadmits that more data is required to make adefinitive stance. Their “no boundary” theoryexplains that the universe is finite, self-contained in space and imaginary time. It alsoimplies that what had a beginning must alsohave an end.

Famous for his great sense of humor, Hawk-ing recounts the story of giving a presentation onthe “beginning of time” in Japan, where hissponsors requested that he “not mention thepossible re-collapse of the universe, because itmight affect the stock market.” Hawking’s replywas to reassure “anyone who is nervous abouttheir investment that it is a bit early to sell,”because the eventual end will not happen forabout 20 billion years.

Hawking also made headlines for his workon black holes, which are formed when stars be-come so dense that nothing can escape theirgravitational fields, including light. This idea ofblack holes was originally proposed in 1783 bythe English scientist John Michell (1724–93) atCambridge, then independently shortly there-after by PIERRE-SIMON, MARQUIS DE LAPLACE inhis publication The System of the World. Neitherof them, nor anyone else in the scientific com-munity, took the ideas beyond their initial pub-

lications. Einstein’s theory of general relativitywas the next theory to address gravity and its ef-fect on light. Then, in 1928, SUBRAHMANYAN

CHANDRASEKHAR worked out his theory of howstars maintain themselves with their own grav-ity, and determined that once a star reaches acertain level of density, known as the Chandralimit, it can no longer support itself. Eddingtonrebuked this idea, but the idea of gravitationalcollapse was revived again in 1939 by RobertOppenheimer (1904–67), then dropped duringWorld War II, and rediscovered in the 1960s.

The resulting work was supported by gen-eral relativity, and suggested that light emittedfrom a dense enough star would turn back in onitself. This light, and everything else within itsproximity, would be pulled into the field. AnAmerican scientist named John Wheeler labeledthis phenomenon a black hole in 1969, and theboundary surrounding the black hole is called itsevent horizon. Hawking first proclaimed in hisresearch that by its nature, a black hole emitsnothing—it only devours, it does not spit out.But he later discovered, with the prodding of anAmerican student at Princeton and two Russianscientists, that black holes actually emit parti-cles and radiation, and in this emission of en-ergy, there is a loss of mass, meaning the blackhole will actually get smaller and smaller andeventually just evaporate, in a period of about1067 years.

In addition to creating theories on theworkings of the universe, Hawking gives pre-sentations on such topics as time travel, pre-dicting the future of the cosmos, and life else-where in the universe. Time travel involves thegeneral theory of relativity, quantum theory, theuncertainty principle, and discussion of cosmicstrings, and wormholes, along with such prac-tical observations as the fact that we have notyet been flooded by time-traveling tourists fromthe future. He similarly discusses Einstein’s fa-mous quote “God does not play dice,” and giveshis theories on this postulate, based, of course,

150 Herschel, Caroline Lucretia

on scientific principles, to determine whetherthis is true and/or if it is possible to predict thefuture of the universe. The second law of ther-modynamics, a definition of life, and a princi-ple called the anthropic principle, along withinformation on the Big Bang, the makeup ofDNA, and some comments on evolution, stokethe fire of his discussion of the question of lifeoutside our solar system. This proprietary in-formation can be found on his Web site,http://www.hawking.org.uk.

Hawking’s famous book A Brief History ofTime was published in 1988, and became an in-ternational best seller, translated into more than40 languages, and selling more than 9 millioncopies. He updated the book with a new versionentitled The Illustrated A Brief History of Time,in 1996, and also published in 2001 a book en-titled The Universe in a Nutshell. He has also pub-lished numerous technical papers, all of whichrequire a professional foundation in physics inorder to understand. The Theory of Everything:The Origin and Fate of the Universe is a new com-pilation of his work, much of which is in printin A Brief History of Time, and is a book in whichhe emphatically states he did not authorize anddoes not endorse.

A father of three, Hawking left his wife in1990 and remarried in 1995. When asked howhe feels about his disease, his standard answer is“Not a lot. I try to lead as normal a life as pos-sible and not think about my condition, or re-gret the things it prevents me from doing, whichare not that many.” Remembering the early daysof his diagnosis and the boy who shared hisroom, Hawking has a strong reminder of howfortunate he is. “Whenever I feel inclined to besorry for myself, I remember that boy.”

Hawking continues to travel around theworld, giving public lectures and attending sci-entific conferences and symposiums. He hasbeen awarded 12 honorary degrees, and is amember of the Royal Society and the U.S.National Academy of Sciences.

5 Herschel, Caroline Lucretia(1750–1848)GermanAstronomer

Caroline Lucretia Herschel has often been men-tioned only in reference to “assisting” her famousastronomer brother, SIR WILLIAM HERSCHEL, yetit was her calculations, her energy, and her ded-ication to astronomy that led to her importantcontributions to the field, including the compi-lation of two catalogs and the discovery of thefirst comet ever found by a woman, winning herthe praise of kings.

Born in 1750 in Hanover, Germany, Herschelwas brought up in the somewhat traditional wayused in rearing female children at the time. Hermother, Anna Ilse Moritzen Herschel, believedthat girls should be raised to learn only house-hold tasks, and was opposed to any education ofher daughter. Her father, Isaac Herschel, was notnecessarily in agreement, but given his wife’s dis-position and the large number of children towhich the family had to attend, reported as sixto 10 depending on the source, he gave as muchattention to providing some knowledge to hisdaughter as time and his wife would allow. Mostimportant, he introduced her to the stars, “tomake me acquainted with several of the beauti-ful constellations, after we had been gazing at acomet,” she wrote in her diary. But her fatherleft the family’s home to fight the French whenshe was only seven years old, and returned threeyears later much worse for the wear. The younggirl was obliged to take on the role her motherprescribed, strictly relegated to household choresand tending to her ill father for the next 10 years,until he died in 1767.

The Herschel family was steeped in music.Isaac had been in the Hanoverian Foot Guard,first as oboist and then eventually as bandmas-ter, and Herschel’s older brother William, whoplayed a profound role in her life, became amember of the band as well before leaving

Herschel, Caroline Lucretia 151

home and becoming a music teacher in Bath,England.

In 1772, at age 22, Caroline Herschel de-cided to leave behind a life of knitting, dress-making, and studies to become a nanny. Herbrother William invited her to come and livewith him in Bath. Over the next few years, inexchange for her help running William’s house-hold, a task at which by this time she excelled,the organist, composer, and music teacher gavehis sister singing lessons, and began to indoctri-nate her in the higher education that she was sosuited to absorb, including English, algebra,geometry, spherical trigonometry, and astron-omy. So much for her mother’s ideas.

It is said that William’s interest in astron-omy was spurred shortly after his sister’s arrival,in 1773, when at age 35 he bought a book byJames Ferguson entitled Astronomy Explainedupon Sir Isaac Newton’s Principles, and MadeEasy to Those Who Have Not Studied Math-ematics. This book was also the inspiration forRobert Baily Thomas to create the OldFarmer’s Almanack 20 years later, in 1793,which is still in publication today and has thedistinction of being the longest-running al-manac in history.

Apparently it took William next to no timeto get hooked on astronomy, because before theyear was over, he and his sister, along with theirbrother Alexander, who was also living withthem at the time, began working on buildingtheir own telescopes. Herschel claims that“nearly every room in the house [was] turnedinto a workshop,” for some aspect of production.And while the reality of seeing the house in ashambles “was to my sorrow,” she managed towork around it and became quite good at grind-ing telescope mirrors. The resulting telescopes,most notably a seven-foot model, turned abrother’s interest in peering at the night sky asoften as the British weather would permit intowhat would become a lifelong family affair.Over the years, they continued to make and sell

telescopes, but studying the stars was their mainventure.

With William manning the eyepiece, thefamily’s goal was to do a systematic survey of thesky. Herschel wrote down all of the measure-ments William called out or signaled to her, andthen did the daily calculations and logged all oftheir findings. Her daily duties still included run-ning the household, and by now she had alsobecome an accomplished singer, giving perform-ances as often as five times a week with herbrother. But the most important thing seemedto be taking care of their work with the stars.Herschel noted that “every leisure moment waseagerly snatched at for resuming some workwhich was in progress.”

In March 1781 Herschel was recording datafrom her brother as he observed a comet in thenight sky. But calculations proved that this wasnot a comet at all. The pair had discovered anew planet, as far beyond Saturn as Saturn isfrom the Earth. “William’s” discovery of theplanet, eventually named Uranus the father ofSaturn, Saturn being the father of Jupiter, cata-pulted the Herschel duo from local amateur as-tronomers to national treasures. King George IIIgave William an annual salary of £200, and as anew member of the Royal Society Williamdecided to leave the music business for good, go-ing from professional musician to professional as-tronomer overnight. While Herschel loathedgiving up her singing career, she acquiesced, al-though she enjoyed singing privately through-out the rest of her life, and sometimes for verynoble guests.

The following year, Herschel’s brothermoved them into a bigger house in Windsor, andshe became the owner of a new telescope of herown, a gift from William so that she could startmaking her own observations. As she hadlearned with her brother, the best approach wassystematic, so she began to methodically trackthe night sky in search of comets. But her workwith her brother continued to occupy most of

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her time. He became more immersed in his ownobservations, and she was always present, record-ing data during night-time observations and cal-culating the work during the day. For the nextseveral years, she spent most of her time record-ing and working on computations with herbrother as he did work that led to discoveries ofnew binary stars, new moons, and eventually thedoubling of the size of the known solar system.

Her own discoveries occurred, however, af-ter a move in April 1786 to another house, ahome they called Observatory House. Here, onAugust 1, 1786, Caroline Herschel discoveredher first comet. She became instantly famous.Her comet was dubbed “the first lady’s comet,”because Herschel was in fact the first “lady” toever discover a comet.

This began an entirely new life for Herschel.In 1787 the king gave her a £50 annual salary,and the Herschels became frequent guests at thecastle. Princess Augusta would often peer into atelescope at the castle, and would invite gueststo look and see “Miss Herschel’s comet.”

That same year, Herschel’s brother marriedand, understandably, it was time for Herschel toleave her brother’s house and make a home ofher own. She was reportedly furious and bitterwith her brother’s wife for insisting that sheleave, but she moved within walking distanceand came to their house every day to work onhis observations. Eventually, she softened towardher sister-in-law, and things smoothed out be-tween them, especially after the birth ofWilliam’s son John in 1792. As her nephew grew,Herschel was able to start teaching him mathe-matics and astronomy—a task that resulted inthe formation of another renowned scientistin the family, SIR JOHN FREDERICK WILLIAM

HERSCHEL.Herschel continued both her work with her

brother and her search for comets, discovering atotal of eight comets during the next 11 years.She also embarked on another huge project,working on updating Royal Astronomer John

Flamsteed’s Historia Coelestis Britannica star cat-alog. In 1798 she presented her first publication,Index to Flamsteed’s Observations of the FixedStars, in which she updated his catalog with 560stars that were not previously included. Thiswould be her sole publication for the next 25years.

In 1822 William Herschel passed away, andCaroline, now 72, left England to live the restof her years in Hanover. By 1828 her next pub-lication was ready to be presented to the world.A catalog that she put together in part to helpher nephew with his own astronomical contri-butions, the work was a compilation of 2,500nebulae. This was a great achievement that wasrecognized with a gold medal in 1828 from theRoyal Astronomical Society. In 1832 William’swidow died, and their son John went to Hanoverto visit his aunt, now aged 83, marveling thatthe petite woman “runs about the town with me,and skips up her two flights of stairs,” sings,dances, and is full of life “quite fresh and funnyat ten p.m.”

The effervescent Herschel remained alertand active for many years to come. She was hon-ored in 1835 when she and MARY FAIRFAX

SOMERVILLE jointly became the first two womenelected to the Royal Society. Leading scientistscontinued to visit her throughout her life, andshe remained a celebrity for her amazing workin astronomy. In 1838 the Royal Irish Academyelected her a member, and her 96th birthday wasmarked with a gift from the king of Prussia, agold medal for her scientific achievements.

At her 98th birthday celebration, the crownprince and princess of Prussia visited Herschelat her home, where she said, “Let’s sing a catch,”and proceeded to perform a song written muchearlier in her lifetime by her brother William.She remained active and alert until her death athome on January 9, 1848, where she drifted awaypeacefully. The first home that she shared withher brother William in Bath, located at 19 KingStreet, is now the site of the William Herschel

Herschel, Sir John Frederick William 153

Museum. In addition to her many awards, a mi-nor planet was named Lucretia in 1889 in herhonor, and a crater on the Moon bears her name.

5 Herschel, Sir John Frederick William(1792–1871)BritishMathematician, Astronomer

Sir John Herschel had such a wide range of in-terests in his life that he could easily be consid-ered a Renaissance man of the Victorian age.He influenced many of the great minds of histime, including Charles Babbage (1791–1871),Charles Darwin (1809–82), and Michael Faraday(1791–1867). But as diverse as his interests were,many of them melded seamlessly together allow-ing him to make some of the greatest contribu-tions in his life to astronomy—both inheritingand passing on his family’s legacy of extraordi-nary scientific achievement.

John Frederick William Herschel was bornon March 7, 1792, to Mary Pitt Herschel andthe famous “King’s Astronomer” SIR WILLIAM

HERSCHEL. He was Mary’s second child, from hersecond marriage. Mary’s first husband and childdied, leaving her a young widow until she mar-ried William in 1788. William’s only child, theboy was raised in the home they calledObservatory House, where William had built his40-foot telescope with a £4,000 grant from theking.

Education began early in Herschel’s life.CAROLINE LUCRETIA HERSCHEL, at that time oneof the most famous women in the world, dotedon her nephew and took every opportunity toteach him science and mathematics during herdaily visits to Observatory House. Herschel’s of-ficial schooling started at Dr. Gretton’s School,in the town of Hitcham, where he went untilthe age of eight, when he changed to EtonCollege. But as the new boy in school, Herschelsoon found himself a target for bullies, and his

mother pulled him out within a few months,turning to private tutoring for her son’s educa-tion. At the age of 17, in 1809, Herschel wentto St. John’s College at Cambridge.

Mathematics was the field of choice forHerschel at Cambridge, and he teamed up withtwo other brilliant students to force changes inthe way mathematics was being taught inEngland. In 1812 he and classmates Babbage andGeorge Peacock (1791–1858) formed an organ-ization they called the Analytical Society, hop-ing to create enough of a critical mass to con-vert the British educational system over tomodern mathematics, specifically the teachingsof Sylvestre Lacroix (1765–1843). Herscheltranslated from French Lacroix’s treatise on cal-culus, and added his own examples to the work.The society was short-lived, but the translationwas successful, and the work was adopted as atextbook, giving Herschel his first of many im-pressive successes.

While working on changing the educationalsystem, the 20-year-old undergraduate studentpublished his first paper—a mathematics pieceentitled, “On a Remarkable Application ofCotes’s Theorem”—in the Transactions of theRoyal Society. The following year, after graduat-ing from Cambridge in 1813, Herschel waselected a Fellow of the Royal Society based onthe merits of his paper.

After graduation, Herschel took a detourfrom science and decided to become a lawyer.He studied for about a year and a half, then aban-doned the law and returned to Cambridge. In1816 he graduated from Cambridge again, thistime with an M.A. in mathematics, and wentback home to spend the summer with his 78-year-old father. This visit was a turning pointin Herschel’s professional life. He wrote toBabbage, saying that he was going back toCambridge just long enough to pack up and takecare of his personal affairs, and then “I am go-ing under my father’s directions . . . and con-tinuing his scrutiny of the heavens.”

154 Herschel, Sir John Frederick William

But while Herschel was committed to fol-lowing in his father’s footsteps, he was not quiteready to give up his other interests—and he hadmany. One of them was photography. In 1819Herschel began experimenting with “photogra-phy,” a term that he made up. Interested inchemistry, Herschel had done many experi-ments with chemicals as they related to pho-tography. He published his experiments, andthey would prove to have a profound impact onthe development of photography in about 20years.

In 1820 Herschel began to make some seri-ous inroads in astronomy. He joined his father atthe first meeting of the Astronomical Society ofLondon—the precursor of the Royal Astronom-ical Society—and his father became the firstpresident of the society, with Herschel elected asvice president. That same year, he published abook coauthored with Babbage, A Collection ofExamples of the Applications of the Differential andIntegral Calculus. In 1821 the Royal Societyawarded him his first Copley Medal for his pub-lications.

But the collaborations with his famous fam-ily came to a sudden halt when, in 1822, his fa-ther died and his aunt Caroline moved back toGermany. Left to make his name in astronomyon his own, Herschel published his first astro-nomical paper, in which he described a new wayto calculate lunar eclipses. He also spent sometime studying light at a time when physicists werebeginning to look at the spectra of nonsolar light.His experiments dealt with the spectra of metal-lic salts, in which he could determine that therewere small quantities of salt in flames. This workmarked the beginning of a new branch of physicscalled spectroscopy.

By 1824 Herschel was fully engaged inastronomy. He was elected secretary of the RoyalSociety, a position he kept for three years. Hepublished his first major book, a catalog of dou-ble stars in the Transactions of the Royal Society,for which he received the Paris Academy’s

Lalande Prize the following year and the Astro-nomical Society’s gold medal. Then, in 1826, hebegan to focus his work on binary stars, whichhad been a major component of his father’swork. He took time out only to write, and tomarry a woman named Margaret Brodie Stewardin 1829.

Herschel began to make many importantcontributions to encyclopedias, writing about sci-entific subjects to help educate the masses. Hisfirst such piece was a 245-page work on light, writ-ten in 1828, for the Encyclopaedia Metropolitana.Next came similar articles on mathematics for the1830 edition of the Edinburgh Encyclopaedia. Thatsame year, Herschel published one of his most fa-mous works, Preliminary Discourse on the Study ofNatural Philosophy, a book that influenced Darwinand prompted Faraday to write to Herschel tellinghim that the book “made me, if I may be per-mitted to say so, a better philosopher.” The fol-lowing year, Herschel was knighted. Then, in1832, his mother died.

Herschel continued concentrating on thework his father had started with binary stars, andhe devised a way to determine their orbits anddiscovered that they orbited a common centerof gravity. He was awarded the Royal Medal fromthe Royal Society in 1833, for his paper “Onthe Investigation of the Orbits of RevolvingDouble Stars.” He also published A Treatise onAstronomy as an encyclopedia entry.

Heavily engrossed in carrying on his father’swork, Herschel packed his family, consisting ofhis wife and four children, and the 20-foot re-fractor telescope that he and his father hadbuilt, and sailed for the Cape of Good Hope inSouth Africa, where the Royal Observatory hadbuilt a new facility in 1828, with a mission ofcataloging the heavenly objects that could notbe seen in the Northern Hemisphere. He arrivedin January 1834, and set up observations inFeldhausen, near Cape Town.

The next few years were busy for Herschel.In South Africa he was able to observe and chart

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the kinds of “exotic objects” that his fatherfound so fascinating, nebulae and star clusters.An exceptional artist, he drew many of the ob-servations he saw in the Southern Hemispheresky. He had the extreme good fortune of beingable to observe the return of Halley’s comet in1835, and he noticed that there seemed to besomething other than gravity that affected itsorbit, deciding that it was somehow being re-pelled by the Sun. In truth, the repulsion heobserved was caused by solar wind, leadingmany to believe that Herschel was the first todiscover this unseen but documented force. Healso discovered that the comet was expellingevaporated gases.

In 1836 Herschel worked on establishingthe relative brightness of nearly 200 stars. Heused the Moon as a focal point and comparedstars and their apparent brightness as they re-lated to the distance of the Moon and its ap-parent brightness. In 1833 a paper he publishedon nebulae and star clusters in the PhilosophicalTransactions earned him another Royal Medalfrom the Royal Society. During his last two yearsin South Africa, Herschel also worked on meas-uring solar energy, and in 1838, loaded with datafrom his years of Southern Hemisphere observa-tions, he headed home to England.

The next several years were full of big ad-vancements in photography, and Herschel puthimself right in the middle of it. A good friendof his, William Henry Fox Talbot (1800–77),who is credited as the inventor of this field, con-sulted with Herschel many times, as the two dis-cussed the new inventions Talbot was making.Herschel is credited with discovering that hy-posulfite of soda could be used as a photographicfixative, and for devising the terms negative andpositive for paper photos. Seeing the obvious ben-efits of the new realm of photography, Herschelsoon became a very vocal advocate for its use inastronomical observations. He wrote a paper in1839, “On the Chemical Action of the Rays ofthe Solar Spectrum on Preparations of Silver,

and Other Substances, Both Metallic and Non-Metallic, and on Some Photographic Processes,”printed in the Philosophical Transactions, which,in 1840, earned him another Royal SocietyRoyal Medal.

In 1842 he left photography in the capablehands of Talbot and others and got back to thebusiness of compiling his data from SouthAfrica. During this time, he became head of theMarischal College in Aberdeen, and then,three years later, in 1845, president of theBritish Association at Cambridge. In August1846 he heard about a new planet that fellowastronomer JOHN COUCH ADAMS had deter-mined existed beyond Uranus, which was theplanet Herschel’s father had discovered.Herschel was elated by the news, and did every-thing he could to help Adams get support inhis search for the planet, including setting upa presentation for Adams at a meeting of theBritish Association, for which Adams arrivedthe day after the meeting. When the LondonTimes ran the headline “Le Verrier’s PlanetFound” on October 1, 1846, Herschel notifiedthe press that this new planet, ultimatelynamed Neptune, was really Adams’s planet,which started an international incident.

When he was not involved in the Adamsscandal, Herschel continued working on his ob-servations, computations, and compilations, andin 1847, he published Results of AstronomicalObservations Made during the Years 1834, 1835,1836, 1837, and 1838, at the Cape of Good Hope,Being the Completion of a Telescopic Survey of theWhole Surface of the Visible Heavens, Commencedin 1825. This work resulted in his second CopleyMedal from the Royal Society. In 1847, he alsoimproved a device called a calorimeter, used tomeasure the heat from a chemical reaction,which had been originally constructed in 1783by Antoine Lavoisier (1743–94) and PIERRE-SIMON, MARQUIS DE LAPLACE.

In 1849 Herschel expanded his work intothe Outlines of Astronomy, originally written as

156 Herschel, Sir William

an encyclopedia entry in an in-depth textbook,and it was an instant success. The book had 12editions in England, was translated into manylanguages, and was used as a textbook aroundthe world for decades to come.

As strange as Herschel’s detour into lawseemed in the beginning of his career, he madeperhaps an even more bizarre stray from his sci-entific endeavors in 1850, when he decided totake on the role of Master of the Mint. For thenext 13 years, Herschel overworked himself inthis position, and turned to writing poetry, muchof which was published in 1857; and some sci-entific work, published in 1861, on meteorology,geography, and telescopes. In 1863 he finally re-tired from his duties at the mint. His biggest pub-lication was still to come.

In 1864 Herschel published his GeneralCatalogue of Nebulae and Clusters, listing 5,097star clusters and nebulae, of which 4,630 werediscovered by Herschel and his father through-out their careers. This was revised in 1888 by L.E. Dreyer into the New General Catalogue (NGC)with 7,840 nebulae and clusters. The NGC num-bers are still used to identify nonstellar objects.Herschel followed this work in 1866 with a gen-eral publication entitled Familiar Lectures onScientific Subjects.

Herschel’s life was full of accomplishment,fueled in part by the diversity of interests thatkept his mind active, including astronomy, biol-ogy, chemistry, education, language, mathemat-ics, music, poetry, philanthropy, physics, andpublic service. As a respected scientist, he cor-responded with some of the most brilliant mindsof the time.

Nearly all of Herschel’s documents have sur-vived, including a collection of 10,000 letters (ofwhich 75 percent are from the world’s leadingscientific minds of the time), his astronomicalobservations, diaries, books, laboratory notes,and a collection of his photographic work. Hewon multiple awards for his contributions to sci-ence in both mathematics and astronomy, and

was involved in many organizations to help fur-ther the sciences.

Craters on the Moon and on Mars arenamed for this extraordinary scientist, who diedon May 11, 1871, in Kent, England, and wasburied in Westminster Abbey. Herschel had 12children. His son, Alexander, became a profes-sor of physics and carried on the Herschel tra-dition of working with the Astronomer Royal,advocating with George Biddell Airy (1801–92)the use of photography in astronomy.

5 Herschel, Sir William (Friedrich Wilhelm Herschel)(1738–1822)GermanAstronomer

Sir William Herschel is the epitome of an ama-teur astronomer who turned a passion for hishobby into his life’s work. Thanks to a book thatcaught his interest at age 35, and the help of hissister, Caroline, Herschel went from being a mu-sician and amateur astronomer to being theKing’s Astronomer in just nine years. He also be-came the last person to discover a planet purelyon observation rather than on mathematicalcomputation.

Friedrich Wilhelm Herschel was born onNovember 15, 1738, in Hanover, Germany, toAnna Ilse Moritzen Herschel, the strict matri-arch of her family, and Isaac Herschel, an oboistwho eventually became the bandleader of theHanoverian Foot Guard. In 1750, whenHerschel was 12 years old, his sister Caroline wasborn, and in a little more than 20 years shewould begin to play a profound role in his suc-cess as an astronomer.

The young Herschel was a dedicated musi-cian, and as a teenager joined the HanoverianGuard to be in the band with his father. But mil-itary bands are first and foremost military, andwhen the Seven Years’ War broke out, Herschel

Herschel, Sir William 157

and his father were called to duty in 1757 tofight at the battle of Hastenbeck.

Fighting in a war took its toll on both fa-ther and son. The elder Herschel did everythinghe could to help his son get out of the war, andin 1759, Herschel left Germany for England,where he would spend the rest of his life. Heearned a living as a traveling musician, stoppingin Halifax in 1765 and working as an organistfor a year, then settling in Bath, England, wherehe became the organist at the Octagon Chapeland eventually acquired a job as city public con-certs director.

Meanwhile, Isaac Herschel continued fight-ing, and when he finally returned home in 1760,he was in need of constant care. Caroline tookcare of their father until 1767, when he passedaway.

Working successfully in Bath, Herschel be-came a music teacher, composer, and conductor.By 1772 he was a well-respected member of hiscommunity. Back home in Germany, Herschel’ssister Caroline, who had so diligently tendedtheir father, was now serving her overbearingmother, taking care of the household chores, andstudying to become a nanny.

Herschel needed help running his house-hold, so in 1772 he invited his 22-year-old sis-ter to live with him in England. She jumped atthe chance, and moved to England to joinHerschel and one of their brothers, Alexander,in Bath. Herschel was soon teaching his sistermusic, and she began singing in concerts the twowould give throughout the week.

But Herschel did more for Caroline thanteach her music. He soon introduced her to thekind of intellectual stimulation that she hadlonged for as a child but was denied because theirmother did not believe that girls should be ed-ucated. To their mutual benefit, he taught hissister algebra, geometry, trigonometry, and as-tronomy.

On May 10, 1773, Herschel purchased a bookthat would forever change his life, his sister’s life,

and the size of the known universe. AstronomyExplained upon Sir Isaac Newton’s Principles, andMade Easy to Those Who Have Not StudiedMathematics, written by James Ferguson, put aburning desire in Herschel to study the stars. Butin order to study them, Herschel needed a tele-scope, so he collected used parts and built one. Itwas small. It was also inadequate.

Encouraged, he enlisted the help of his sib-lings to build a bigger telescope, and Herschel,Caroline, and Alexander proceeded to turn theirhome into their own private telescope manu-facturing facility. Caroline became adept atgrinding mirrors, while Alexander helped withthe overall construction. The family became sogood at their avocation that they started sellingtheir telescopes to other amateur astronomersand even to the Royal Observatory.

By 1774 they had constructed a seven-foottelescope, and Herschel started studying theheavens. Meticulous and methodical, Herscheldevised a plan to study a strip of sky at a time.Standing on a ladder, peering into the telescope,he told his sister everything he saw, and sherecorded it all in great detail. For the next sev-eral years, the brother-and-sister team observedthe night sky as often as they could, concerts andlocal weather permitting, and Caroline recordedby night and computed by day in addition tomanaging the house.

This was an interesting time in the evolu-tion of astronomy—a time when the observa-tions that had been made up to this point werebeing compiled into useable data for navigatorsat sea. Certainly, Herschel’s work could eventu-ally be useful for navigators, but while that wasthe sole purpose of the work being done at theRoyal Observatory, it was not the foremostthought on Herschel’s mind. He wanted to makea systematic survey of the stars, and he set aboutobserving and documenting everything he saw,with his sister’s diligent help.

On the evening of March 13, 1781,Herschel was peering though his seven-foot

158 Herschel, Sir William

telescope, equipped with a 6.2-inch reflector, atthe constellation Gemini, when he saw a disk-shaped light shining back at him. He observedthe object as it moved slowly across the sky, andwas convinced that he had discovered his firstcomet. His sister wrote down the observationsand performed the calculations as the objectcontinued to move in the night sky.

But the “comet” was beyond Saturn, and ifit really were a comet, it would have been toosmall to see. Herschel’s suspicions were not cor-rect. The Royal Observatory’s fifth AstronomerRoyal, Nevil Maskelyne, discovered thatHerschel’s “comet” was, instead, a planet thatwas farther beyond Saturn than Saturn is fromthe Sun. And since the galaxy and the universewere considered to be the same at this point inhistory, Herschel’s discovery doubled the knownsize of the universe. Herschel commented, “Itwas this night its turn to be discovered.”

Astronomers from around the world wereready to pounce on the chance to name the newplanet, and the English were afraid that theFrench would steal the opportunity if Herscheldid not come up with something fast. SoHerschel suggested the most politically correctname he could think of: Georgium Sidas, theGeorgian Planet, to honor the reign of KingGeorge III. Unfortunately, King George was notas beloved outside of England, so the Frenchgave it their own name—Herschel. Other sug-gested names included Minerva, for the Romangoddess of wisdom, and Hypercronius, whichmeans “above Saturn.” But the Germans, whohad nothing to do with the discovery, seemed tobe very adept at naming things and JOHANN

ELERT BODE took the logical approach andnamed the planet Uranus, who in mythology wasthe son of Gaia (the Earth), and the father ofSaturn. The various countries continued callingthe planet by the names they liked best until1850, when JOHN COUCH ADAMS, who discov-ered Neptune, proposed that it should have theofficial name of Uranus.

But what’s in a name? It was the discoverythat counted. Saturn had been the farthestknown planet, at a distance of 886,200,000miles from the Sun. Uranus, a little less thanhalf the size of Saturn, about four times as bigas the Earth, was 1,782,000,000 miles from theSun. This discovery was worthy of some recog-nition, even if an amateur made it. Within afew short months, on December 7, 1781, theRoyal Society elected Herschel into its ranks asa Fellow, and Herschel was appointed the“King’s Astronomer,” and was given a lifetimesalary of £200 per year by King George. The fol-lowing year, in May 1782, Herschel and his sis-ter quit the music business forever, and inAugust they moved into a bigger house in thetown of Datchet, where they lived for nearlythree years.

During their time in Datchet, Herschel fo-cused his attention on new heavenly bodies. Afriend named William Watson had givenHerschel a copy of CHARLES MESSIER’s catalog ofstar clusters and nebulae as a congratulatory giftupon his election into the Royal Society.Herschel was now interested in observing these“exotic objects,” as he called them. In 1782 heand Caroline began their work on surveying thesky for these nebulae, and as a gift he gave hissister a telescope of her own. For the next fewyears, the duo worked diligently on recordingand classifying their observations, being carefulnot to duplicate the work of Messier.

In 1785 Herschel and Caroline movedagain, this time to Windsor to be near the king.Herschel was working on his theories about theshape of our galaxy. The small telescopes he hadused up to this time were adequate for the workhe had done, but his needs were now outgrow-ing his technology. So the king offered Herschelhis patronage again, this time in the form of a£2,000 grant to build a telescope that would be-come the world’s largest—a 40-foot reflector.

In April 1786 the Herschel siblings movedfor the last time together, into a home they

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called Observatory House in Slough. The movewas a good one for both of them. Herschelstarted the process of building his new impres-sive telescope, and in August Caroline made herfirst discovery—a comet. She was the firstwoman ever to make such a discovery. It wasdubbed “the first lady’s comet,” and she wasawarded her own salary of £50 per year from theking. From this point on, the two were frequentguests at the palace.

Herschel’s next two big discoveries occurredin 1787, when he found the first two satellitesof his planet, Titania and Oberon. The next two,Ariel and Umbriel, were discovered in 1787 byanother British astronomer, and these fourmoons were eventually named by Herschel’s son.The fifth moon, Miranda, was discovered in1948 by GERARD PETER KUIPER. To date, 22moons have been discovered in its orbit.

The following year marked perhaps thebiggest change of all for the brother and sisterastronomers. Herschel married a young widownamed Mary Pitt, and Caroline was forced tomove out of their home at Mary’s insistence.This was the first time that Caroline had everlived on her own, and she was extremely upset.Eventually she reconciled with her sister-in-lawand regretted her anger. Caroline continued towork with her brother, and walked to his housedaily to record their observations.

Three years and £4,000 after constructionbegan, Herschel’s 40-foot telescope was com-plete. His first discoveries with this new master-piece were Mimas and Enceladus, the sixth andseventh moons of Saturn. He was also now ableto make out some individual stars in some of theglobular clusters he had observed with his olderequipment.

In 1792, at age 55, Herschel became a fa-ther. His son John was born at ObservatoryHouse, and grew up with the 40-foot telescopeas part of his daily life. The boy was influencedby the music and science around him, especiallyby his Aunt Caroline, and eventually joined his

father in astronomical work. In 1864 SIR JOHN

FREDERICK WILLIAM HERSCHEL published TheGeneral Catalogue of Nebulae, a collection ofmore than 5,000 nebulae, of which 4,630 werediscovered by John and his father.

Over the years, Herschel continued his ob-servations of nebulae, star clusters, the Sun, andbinary stars. He found that the Sun was gaseousin nature, observed sunspots, and discovered in-frared light emanating from the Sun. He dis-covered nearly 1,000 binary stars, and proposedthat these stars have a common center of grav-ity around which they rotate. His observationsof nebulae led him to believe that they were clus-ters of stars he called “island nebulae,” and hebelieved that these were “island universes,”galaxies, outside the Milky Way. He was, in fact,the first person to accurately describe the MilkyWay Galaxy, a feat he accomplished using thestatistics he had accumulated during his obser-vations with Caroline.

On January 12, 1820, Herschel attended adinner at the Freemason’s Tavern in London,where a group of 14 men talked about forminga society with the simple goal of promoting as-tronomy. On March 10 the AstronomicalSociety of London, later the Royal AstronomicalSociety, had its first official meeting, andHerschel became its first president.

Herschel was known for his tremendousenthusiasm for astronomy and for his exacting,methodical style of observation of the nightsky. He was knighted in 1816 for his contri-butions to the field of astronomy. On August25, 1822, Herschel died in Slough, England,and was laid to rest at St. Laurence’s Churchin Upton. His work was his life’s gift, and hiscontributions earned him the respect and ad-miration of far more learned men than he. Thehouse Herschel shared with his sister in Bath,the site of the discovery of Herschel’s planet,Uranus, was opened in 1981 as the WilliamHerschel Museum. The remains of his 40-footreflector telescope from Observation House are

160 Hertz, Heinrich Rudolf

now on display at the Royal Observatory inGreenwich. In honor of his work, a crater onthe Moon was named Herschel for this ama-teur astronomer, as was one for his sister andanother for his son.

5 Hertz, Heinrich Rudolf(1857–1894)GermanPhysicist

In 1888 Heinrich Hertz produced and detectedradio waves for the first time. He also demon-strated that this form of electromagnetic radia-tion, like light, propagates at the speed of light.His discoveries form the basis of both the globaltelecommunications industry (including com-munications satellites) and radio astronomy.The hertz (Hz) is the Système Internationale(SI) unit of frequency, named in his honor.

Hertz was born on February 22, 1857, inHamburg, Germany, into a prosperous and cul-tured family. Following a year of military service(1876–77), he entered the University of Munichto study engineering. However, after just oneyear, he found engineering not to his liking andbegan to pursue a life of scientific investigationas a physicist in academia. Consequently, in1878 he transferred to the University of Berlinand started studying physics, with the famousGerman scientist Herman von Helmholtz(1821–94), as his mentor. Hertz graduatedmagna cum laude with his Ph.D. degree inphysics in 1880. After graduation, he continuedworking at the University of Berlin as an assis-tant to Helmholtz for the next three years.

He left Berlin in 1883 to work as a physicistat the University of Kiel. There, following sug-gestions from his mentor, Hertz began investi-gating the validity of the electromagnetic theoryrecently proposed by a Scottish physicist, JamesClerk Maxwell (1831–79). As a professor ofphysics at the Karlsruhe Polytechnic from 1885

In 1888 the German physicist Heinrich Rudolf Hertzbecame the first person to produce and detect radiowaves. He also demonstrated that radio waves, likeother forms of electromagnetic radiation, propagate atthe speed of light. His scientific discoveries laid thefoundation for communications satellites as part of theglobal telecommunications industry and for radioastronomy. (Deutsches Museum, courtesy AIP EmilioSegrè Visual Archives, Physics Today Collection)

to 1889, Hertz finally gained access to the equip-ment he needed to perform the famous experi-ments that demonstrated the existence ofelectromagnetic waves, and he verified Maxwell’sequations. During this period, Hertz not only pro-duced electromagnetic (radio frequency) wavesin the laboratory but also measured their wave-length and velocity. Of great importance to mod-ern physics and the fields of telecommunicationsand radio astronomy, Hertz showed that hisnewly identified radio waves propagated at thespeed of light, as predicted by Maxwell’s theory

Hertzsprung, Ejnar 161

of electromagnetism. He also discovered that ra-dio waves were simply another form of electro-magnetic radiation, similar to visible light andinfrared radiation, save for their longer wave-lengths and shorter frequencies. Hertz’s experi-ments verified Maxwell’s electromagnetic theoryand set the stage for others, such as GuglielmoMarconi (1874–1937) to use the newly discov-ered radio waves to transform the world of com-munications in the 20th century.

In 1887, while experimenting with ultravi-olet radiation, Hertz observed that incidental ul-traviolet radiation was releasing electrons fromthe surface of a metal. Unfortunately, he did notrecognize the significance of this phenomenon,nor did he pursue further investigation of thephotoelectric effect. In 1905 ALBERT EINSTEIN

wrote a famous paper describing this effect, link-ing it to MAX KARL PLANCK’s idea of photons asquantum packets of electromagnetic energy.Einstein earned the 1921 Nobel Prize in physicsfor his work on the photoelectric effect.

Hertz performed his most famous experi-ment in 1888, with an electric circuit in whichhe oscillated the flow of current between twometal balls separated by an air gap. He observedthat each time the electric potential reached apeak in one direction or the other, a spark wouldjump across the gap. Hertz applied Maxwell’selectromagnetic theory to the situation anddetermined that the oscillating spark shouldgenerate a very long electromagnetic wave thattraveled at the speed of light. He also used a sim-ple loop of wire, with a small air gap at one end,to detect the presence of electromagnetic wavesproduced by his oscillating spark circuit. Withthis pioneering experiment, Hertz producedand detected “Hertzian waves”—later calledradiotelegraphy waves by Marconi and then,simply, radio waves. By establishing thatHertzian waves were electromagnetic in nature,the young German physicist extended humanknowledge about the electromagnetic spectrum,validated Maxwell’s electromagnetic theory, and

identified the fundamental principles for wire-less communications.

In 1889 Hertz accepted a professorship atthe University of Bonn. There, he used cathode-ray tubes to investigate the physics of electricdischarges in rarefied gases, again just missinganother important discovery—X-rays—accom-plished by the German physicist WilhelmRoentgen (1845–1923) at Würzburg in 1895.

Hertz was an excellent physicist whose pio-neering research with electromagnetic wavesgave physics a solid foundation upon which oth-ers could build. His major publications includedElectric Waves (1890) and Principles of Mechanics(1894). He suffered from lingering ill health dueto blood poisoning and died as a young man, inhis late 30s on January 1, 1894, in Bonn. In hishonor, the international scientific communitynamed the basic unit of frequency the hertz(symbol Hz). One hertz corresponds to a fre-quency of one cycle per second.

5 Hertzsprung, Ejnar(1873–1967)DanishAstronomer

At the start of the 20th century, Ejnar Hertzs-prung made one of the most important contribu-tions to modern astronomy, when he showed in1905 how the luminosity of a star is related to itscolor, or spectrum. His work, independent ofHENRY NORRIS RUSSELL, contributed to one of thegreat observational syntheses in astrophysics—the famous Hertzsprung-Russell (HR) diagram, anessential tool for anyone seeking to understandstellar evolution.

The Danish astronomer Hertzsprung wasborn on October 8, 1873, in Frederiksberg, nearCopenhagen. His father, Severin Hertzsprung,had graduated with a master of science degreein astronomy, but for financial reasons workedas a civil servant in the Department of Finances

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within the Danish government. Consequently,he encouraged his son to enjoy astronomy as anamateur, believing the field presented very fewopportunities for financial security. Hertzsprungresponded to his father’s well-intended adviceand studied chemical engineering at CopenhagenPolytechnic Institute. Upon graduating in 1898,he accepted employment as a chemical engineerin St. Petersburg, Russia, and remained there fortwo years. He then journeyed to the Universityof Leipzig, where he studied photochemistryfor several months under the German physi-cal chemist Wilhelm Ostwald (1853–1932).The thorough understanding of photochemicalprocesses he acquired from Ostwald allowedHertzsprung to make his most important contri-bution to modern astronomy.

He became one of the great observationalastronomers of the 20th century, despite the factthat he never received any formal academictraining in astronomy. When he returned to

Denmark in 1902, Hertzsprung revived his life-long interest in astronomy by becoming a pri-vate astronomer at the Urania and UniversityObservatories in Copenhagen. During this pe-riod, he taught himself a great deal about as-tronomy and used the telescopes available at thetwo small observatories to make detailed photo-graphic observations of the light from the stars.

Hertzsprung’s earliest and perhaps most im-portant contribution to astronomy started withthe publication of two papers, both entitled “ZurStrahlung der Sterne” (On the radiation of thestars) in a relatively obscure German scientificphotography journal. These papers appeared in1905 and 1907, respectively, and their existencewas unknown to the American astronomer HenryNorris Russell, who would soon publish similarobservations in 1913. Publication of these twoseminal papers marks the beginning of the inde-pendent development of the Hertzsprung-Russell(HR) diagram—the famous tool in modern as-tronomy and astrophysics that graphically por-trays the evolutionary processes of visible stars. Itscreation is equally credited to both astronomers.Hertzsprung’s two papers presented his insightfulinterpretation of the stellar photography data thatrevealed the existence of a relationship betweenthe color of a star and its respective brightness.He stated that his photographic data also sug-gested the existence of both giant and dwarf stars.Hertzsprung then developed these and manyother new ideas over the course of his long careeras a professional astronomer.

Between 1905 and 1913 Hertzsprung andRussell independently observed and reportedthat any large sample of stars, when analyzed sta-tistically using a two-dimensional plot of magni-tude (or luminosity) versus spectral type (coloror temperature), form well-defined groups orbands. Most stars in the sample will lie along anextensive central band called the main sequence,which extends from the upper left corner to lowerright corner of the HR diagram. Giant andsupergiant stars appear in the upper right portion

American astronomer Harlow Shapley (left) appears inthis photograph talking with the Danish astronomerEjnar Hertzsprung (right), during the 1958 Moscowmeeting of the International Astronomical Union.Working independently of the American astronomerHenry Norris Russell, Hertzsprung developed thefamous Hertzsprung-Russell diagram—a useful graphthat depicts the stars arranged according to theirluminosity and spectral classification. (D. Y. Martynov,courtesy AIP Emilio Segrè Visual Archives, ShapleyCollection)

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of the HR diagram, while the white dwarf starspopulate the lower left region. Modern as-tronomers use several convenient forms of theHR diagram to support their visual observationsand to describe where a particular style fits in theoverall process of stellar evolution. For example,our parent star, the Sun, is a representative yel-low dwarf (main sequence) star. Previously, as-tronomers used the term dwarf star to describeany star lying on the main sequence of the HRdiagram. Today, the term main sequence star is pre-ferred to avoid possible confusion with whitedwarf stars—the extremely dense final evolu-tionary phase of most low-mass stars.

While Hertzsprung was still in Copenhagen,he also started making detailed photographic in-vestigations of star clusters. In 1906 he appar-ently constructed his first color versus magnitudeprecursor diagrams based on photographic obser-vations of the Pleiades and subsequently pub-lished such data along with companion data forthe Hyades in 1911. This activity represents animportant milestone in the evolution of theHertzsprung-Russell diagram. The Pleidaes is aprominent open star cluster in the constellationTaurus about 410 light-years distant. The Hyadesis an open cluster of about 200 stars in the con-stellation Taurus, some 150 light-years away.Astronomers use both clusters as astronomicalyardsticks, comparing the brightness of their starswith the brightness of stars in other clusters.Hertzsprung would spend the next two decadesmaking detailed observations of the Pleidaes—afavorite astronomical object used frequently byother astronomers to compare the performanceof their telescopes in the Carte du Ciel as-trophotography program that began in 1887.

In 1909 the German astronomer KARL

SCHWARZSCHILD invited Hertzsprung to visithim in Göttingen, Germany. Schwarzchildquickly recognized that Hertzsprung, despite hislack of formal training in astronomy, possessedexceptional talents in the field and gaveHertzsprung a staff position at the Göttingen

Observatory. Later that year Schwarzschild be-came the director of the Astrophysical Obser-vatory in Potsdam, Germany, and he offeredHertzsprung an appointment as a senior as-tronomer. Hertzsprung proved to be a patient,exacting observer who was always willing to domuch of the tedious work himself. While at thePotsdam Observatory, he investigated theCepheid stars in the Small Magellanic Cloud.He used the periodicity relationship for Cepheidvariables announced in 1912 by HENRIETTA

SWAN LEAVITT to help him calculate intergalac-tic distances. Although the currently estimateddistance (195,000 light-years) to the SmallMagellanic Cloud is about six times larger thanthe value of 32,600 light-years that Hertzsprungestimated in 1913, his work still had great im-portance. It introduced innovative methods formeasuring extremely large distances and pre-sented an astronomical distance that was signif-icantly larger than any previously known dis-tance in the universe. This “enlarged view” ofthe universe encouraged other astronomers, suchas HEBER DOUST CURTIS and HARLOW SHAPLEY,to vigorously debate its true extent.

Hertzsprung left the Potsdam Observatory in1919 and accepted an appointment as associatedirector of the Leiden Observatory in theNetherlands. He became the director of the ob-servatory in 1935 and served in that positionuntil he retired in 1944. Upon retirement, he re-turned home to Denmark. He remained activein astronomy, primarily by examining numerousphotographs of binary stars and extracting pre-cise position data. The international astronom-ical community recognized his contributions toastronomy through several prestigious awards.He received the Gold Medal of the RoyalAstronomical Society in 1929 and the BruceGold Medal from the Astrophysical Societyof the Pacific in 1937. After a full life dedi-cated to progress in observational astronomy,Hertzsprung, the chemical engineer turned as-tronomer, died at the age of 94 on October 21,

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1967, in Roskilde, Denmark. The Hertzsprung-Russell diagram permanently honors his impor-tant role in understanding the life cycle of stars.

5 Hess, Victor Francis(1883–1964)Austrian/AmericanPhysicist

As a result of ionizing radiation measurementsmade during perilous high-altitude balloonflights between 1911 and 1912, Victor Hess dis-covered the existence of cosmic rays that con-tinually bombard Earth from space. Scientistsused his discovery to turn Earth’s atmosphereinto a giant natural laboratory—a clever re-search approach that opened the door to manynew discoveries in high-energy nuclear physics.

Hess was born in Waldstein Castle, near Peg-gau, in Steiermark, Austria, on June 24, 1883.His father, Vinzens Hess, was a royal forester inthe service of Prince Öttinger-Wallerstein. Hesscompleted his entire education in Graz, Aus-tria—attending secondary school (the Gymna-sium) from 1893 to 1901 and then the Universityof Graz, as an undergraduate from 1901 to 1905,then as a graduate student in physics, from whichhe received his Ph.D. degree in 1910. For approx-imately a decade after earning his doctorate, Hessinvestigated various aspects of radioactivitywhile working as a staff member at the Instituteof Radium Research of the Viennese Academy ofSciences.

In 1909 and 1910 scientists had used elec-troscopes (an early nuclear radiation detectioninstrument) to compare the level of ionizing ra-diation in high places, such as the top of the EiffelTower in Paris, France, or during balloon ascentsinto the atmosphere. These early studies gave avague and puzzling, indication that the level ofionizing radiation at higher altitudes was actuallygreater than the level detected on Earth’s surface.As they operated their radiation detectors farther

As a result of his pioneering ionizing radiation detectionmeasurements made during perilous high-altitudeballoon flights between 1911 and 1912, the Austrian-American physicist Victor Hess discovered the existenceof Höhenstrahlung (radiation from above). These cosmicrays, as they were later called, are very energetic atomicparticles that continually bombard Earth from space.Cosmic rays proved extremely important in nuclearphysics research in the 1920s through the 1950s. Theyalso became a special “window to the universe” thatallowed scientists to examine direct evidence fromviolent astrophysical phenomenon. For his importantdiscovery, Hess shared the 1936 Nobel Prize in physics.(AIP Emilio Segrè Visual Archives, W. F. Meggers Galleryof Nobel Laureates)

from Earth’s surface and the sources of natural ra-dioactivity within the planet’s crust, the scien-tists expected the observed radiation levels tosimply decrease as a function of altitude. Theyhad not anticipated the existence of energeticnuclear particles arriving from outer space.

Hess attacked this mystery by first makingconsiderable improvements in radiation detec-tion instrumentation, which he then took on a

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number of daytime and nocturnal balloon as-cents to heights up to 5.3 kilometers in 1911 and1912. The results were similar, as they were in1912 when he made a set of balloon flight meas-urements during a total solar eclipse. His care-ful, systematic measurements revealed that therewas a decrease in ionization up to about an al-titude of one kilometer, but beyond that heightthe level of ionizing radiation increased consid-erably, so that at an altitude of five kilometersit had twice the intensity than at sea level. Hesscompleted analysis of his measurements in 1913and published his results in the Proceedings of theViennese Academy of Sciences. Carefully ex-amining his measurements, he concluded thatthere was an extremely penetrating radiation, an“ultra radiation,” entering Earth’s atmospherefrom outer space. Hess had discovered “cosmicrays”—a term coined in 1925 by the Americanphysicist Robert Millikan (1868–1953).

Cosmic rays are very energetic nuclear par-ticles that carry information to Earth from allover the Galaxy. When a primary cosmic ray par-ticle hits the nucleus of an atmospheric atom,the result is a cosmic ray “shower” of secondaryparticles that gives nuclear scientists a detailedlook at the consequences of energetic nuclear re-actions.

In 1919 Hess received the Lieben Prize fromthe Viennese Academy of Sciences for his dis-covery. The following year he received an ap-pointment as professor of experimental physicsat the University of Graz. From 1921 to 1923 hetook a brief leave of absence from his positionat the university to work in the United Statesas the director of the research laboratory of theU.S. Radium Company in New Jersey and thenas a consultant to the Bureau of Mines of theU.S. Department of the Interior in Washington,D.C.

In 1923 Hess returned to Austria and re-sumed his position as physics professor at theUniversity of Graz. He moved to the Universityof Innsbruck in 1931 and became the director of

its newly established Institute of Radiology. Aspart of his activities at Innsbruck, he alsofounded a research station on Mount Hafelekarto observe and study cosmic rays. In 1932 theCarl Zeiss Institute in Jena awarded him theAbbe Memorial Prize and the Abbe Medal. Thatsame year, Hess became a corresponding mem-ber of the Academy of Sciences in Vienna.

But his greatest acknowledgment for his pi-oneering research came in 1936 when Hessshared that year’s Nobel Prize in physics for hisdiscovery of cosmic rays. His fascinating discov-ery established a major branch of high-energy as-trophysics and helped change our understandingof the universe and some of its most violenthigh-energy phenomena.

In 1938 the Nazis came to power in Austria,and Hess, a Roman Catholic with a Jewish wife,was immediately dismissed from his universityposition. The couple fled to the United Statesby way of Switzerland and later that year, Hessaccepted a position at Fordham University in theBronx, New York, as a professor of physics. Hebecame an American citizen in 1944 and retiredfrom Fordham University in 1956.

Victor Hess wrote more than 60 technicalpapers and published several books, includingThe Electrical Conductivity of the Atmosphere andIts Causes (1928) and The Ionization Balance ofthe Atmosphere (1933). He died on December 17,1964, in Mount Vernon, New York.

5 Hewish, Antony(1924– )BritishRadio Astronomer

The reception of what were originally thoughtto be signals from an extraterrestrial civilizationled Antony Hewish into a collaborative effortwith SIR MARTIN RYLE resulting in the develop-ment of radio-wave-based astrophysics. Hewish’sefforts involved the discovery of the pulsar, for

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which he shared the 1974 Nobel Prize in physicswith Ryle. The fascinating story starts in August1967, when his graduate student SUSAN JOCELYN

BELL BURNELL detected strangely repetitive“alien” radio wave signals from a certain regionof space during a survey of galactic radio waves.Subsequent analysis indicated the source as apulsar, the first every discovered. Through nofault of Hewish, the 1974 Nobel Prize awards

committee inexplicably overlooked Bell’s role inthis major astronomical discovery.

Hewish was born on May 11, 1924, inFowey, Cornwall, United Kingdom. He receivededucation at King’s College, Taunton, and thenmatriculated in 1942 at the University ofCambridge. From 1943 to 1946 he performedwar service for Great Britain at the RoyalAircraft Establishment in Farnborough and at

British radio astronomers Antony Hewish (left) and Sir Martin Ryle (right) discuss some of their NobelPrize–winning extraterrestrial radio wave data. They shared the Nobel Prize in physics in 1974 for theiraccomplishments in radio astronomy. Hewish received the award primarily for his work identifying the firstpulsar—a feat that started during an August 1967 survey of galactic radio waves and the detection of a suspicious“alien” radio signal by his graduate student Susan Joceyln Bell Burnell. (AIP Emilio Segrè Visual Archives, PhysicsToday Collection)

Hewish, Antony 167

the Telecommunications Research Establish-ment in Malvern, Great Britain. During thisperiod, he participated in the development ofairborne radar-countermeasure devices andworked with Ryle.

He returned to Cambridge University in1946 and completed his undergraduate degree inphysics at Gonville and Caius College two yearslater. Upon graduation, he joined Ryle’s researchteam at the Cavendish Laboratory. In 1952Hewish completed his doctor of philosophy de-gree in physics at Cambridge University andthen lectured at Gonville and Caius Collegeuntil 1961, when he became the director of stud-ies in physics at Churchill College. For the nextthree decades, Hewish continued his affiliationwith Cambridge University, progressing throughpositions of increasing academic importance.From 1961–69 he served as university lecturer,from 1969–71 he became a reader, and then from1971 until his retirement in 1989 he was a pro-fessor of radio astronomy. When Ryle became illin 1977, Hewish assumed leadership of the ra-dio astronomy group at Cambridge and then di-rected the Mullard Radio Observatory from1982–88. Upon retirement, Hewish assumed thetitle of emeritus professor of radio astronomy. Asof 2004 he remained actively involved in con-temporary astrophysical research from his officein the Cavendish Laboratory.

His experiences with electronics, antennas,and radar during World War II influencedHewish to conduct research in radio astronomyfollowing the war. His initial area of interest ad-dressed the propagation of radio waves throughinhomogeneous media. Specifically, he recog-nized that the scintillation twinkling of signalsfrom recently discovered cosmic radio sources(that is, radio stars) could be used to investigateconditions within Earth’s ionosphere. Earth’sionosphere contains various layers of free elec-trons and ions and extends from approximately60 kilometers upward to more than 1,000 kilo-meters altitude. He developed and set up radio

wave interferometers to exploit this idea. Withthis new equipment, Hewish was able to performpioneering measurements that revealed theheight and physical extent of plasma cloudswithin Earth’s ionosphere. In 1964 Hewish’sradio astronomy group at Cambridge Universitydiscovered interplanetary scintillation—thetwinkling or variation in brightness of a cosmicradio source due to radio wave scattering by ir-regularities in the ionized gases within the solarwind. Hewish used this discovery to make thefirst ground-based measurements of the solarwind, and soon space scientists in other coun-tries adopted his technique.

Between 1965 and 1967 he constructed alarge radio telescope at Cambridge with the in-tention of using the facility to survey about1,000 radio galaxies using interplanetary scin-tillation to provide for scintillating radiosources. By a stroke of good luck, this large ra-dio telescope, consisting of a regular array of2,048 dipoles, operated at 3.7 meters wave-length—precisely the wavelength needed tomake astronomical history. On August 6, 1967,one of Hewish’s graduate students, Jocelyn Bell,detected an interesting, rapidly fluctuating ra-dio signal that had a periodicity of approxi-mately 1.337 seconds. Hewish initially thoughtthe unusual signal might be a flare star. But sub-sequent, detailed analysis of the signal indicatedit was a regular radio signal from beyond the so-lar system.

Because of the regularity of the radio wavesignal, it was suggested that this could be a mes-sage from an intelligent extraterrestrial civiliza-tion. So while Hewish puzzled over the natureof this very strange radio signal, both teacherand student decided to call the signal LGM—which stood for “Little Green Man.” As theycontinued to keep track of this signal, Bell de-tected several more pulsed sources. In February1968 they resolved the mystery and announcedthat the strange pulsed radio signal belonged tothe first pulsar ever detected.

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The pulsar is a rapidly spinning neutron starthat had been theoretically postulated in 1934by WILHELM HEINRICH WALTER BAADE andFRITZ ZWICKY. By 1974, when Hewish receivedthe Nobel Prize in physics for the discovery ofthe first pulsar (now formerly identified as PSR1919121 rather than LGM), astronomers haddetected more than 130.

Astrophysicists now believe that a pulsar isa very rapidly rotating neutron star, possiblyformed during a supernova explosion. More than500 radio pulsars are currently known to exist,with periods ranging from 1.56 millisecond to4 seconds. Jocelyn Bell completed her doctoraldegree at Cambridge in 1968 (the same year shemarried Martin Burnell) and included the dis-covery of the pulsar as an appendix in her dis-sertation. Although she did not get any creditfrom the 1974 Nobel Prize committee for herrole in the discovery of the pulsar, Hewish pub-licly acknowledged his student’s “care, diligence,and persistence” in the data collection that ledto this discovery, during his Nobel laureate lec-ture in 1974.

In addition to the 1974 Nobel Prize inphysics, Hewish received other awards andhonors to commemorate his contributions toradio astronomy and astrophysics. His awardsinclude the Eddington Medal of the RoyalAstronomical Society (1969), the FranklinInstitute’s Michelson Medal (1973), and theHughes Medal of the British Royal Society in1976. Hewish became a fellow of the BritishRoyal Society in 1968, a foreign honorarymember of the American Academy of Arts andSciences in 1977, a foreign Fellow of the IndianNational Science Academy in 1982, and an as-sociate member of the Belgian Royal Academyin 1989. As an emeritus professor of radio as-tronomy at Cambridge University, he still en-joys making contributions to astrophysics andgiving inspiring lectures to the general publicthat share the great excitement of scientific dis-covery.

5 Hohmann, Walter(1880–1945)GermanEngineer, Orbital Mechanics Expert

In his seminal 1925 work, The Attainability ofCelestial Bodies (Die Erreichbarkeit der Himme-lskörper), Walter Hohmann described the math-ematical principles that govern space vehiclemotion, including the most efficient, minimum-energy orbit transfer path between two orbits inthe same geometric plane. This widely used orbittransfer technique is now called the Hohmanntransfer orbit in his honor.

Hohmann was born to Rudolph and EmmaHohmann on March 18, 1880, in Hardheim, asmall German town about 40 kilometers south-west of Würzburg. His father served as a physi-cian and surgeon in the local hospital. TheHohmann family moved to Port Elizabeth inSouth Africa in 1891 and remained there forabout six years before returning to Germany.When his family returned to Germany, he en-rolled in high school at Würzburg. Between 1900and 1904 he studied at the Technical Universityin Munich and graduated from there as a certi-fied civil engineer with a Diplom-Bauingenieurdegree.

Upon graduation and for several years there-after just prior to the start of World War I,Hohmann worked as a civil engineer for variouscompanies in Austria and Germany. Then, in1912, he became the combined equivalent of anurban planner and city engineer for the city ofEssen, Germany. It was also in 1912 thatHohmann developed his lifelong interest inspace flight and the motion of spaceships on in-terplanetary trajectories. This fascination withastronautics occurred quite by accident whenthe young engineer read an astronomy book. Asthe clouds of war descended upon Europe, he du-tifully undertook a wartime service position in1915 and performed noncombat activities for ap-proximately eight months.

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He married Luise Juenemann in 1915 and thecouple had two sons, Rudolf (born in 1916) andErnst (born in 1918). In 1916, Hohmann sub-mitted his dissertation on concrete structures tothe Technical University of Aachen. However,because of wartime conditions, his work was notformally accepted and approved until 1919, a yearafter World War I ended. Hohmann could nowuse the more illustrious academic title of “Dr.-Ing.Walter Hohmann”—that is, “Walter Hohmann,Doctor of Engineering”—in his professional ac-tivities.

After World War I Hohmann sought a pro-fessorship in Karlsruhe, but did not succeed. Sohe remained affiliated with Essen as a profes-sional civil engineer for the remainder of hislife. He became a distinguished member ofVerein deutscher Ingenieure, the society ofGerman engineers. The analytical judgmentsand mathematical skills he used to discharge hisprofessional duties also served his work in as-tronautics.

Hohmann’s personal interest in space flightwas reinforced by the great public interest inscience fiction, rocketry, and space travel thatpermeated the Weimar Republic. Some of thisenthusiasm can be attributed to HERMANN JULIUS

OBERTH, who published an inspirational book,The Rocket into Interplanetary Space (Die Rakatezu den Planetenräumen) in 1923. Just afterOberth’s book appeared, Hohmann channeledhis own enthusiasm for astronautics into anotherimportant book. Using his professional mathe-matical and engineering skills, he related the fun-damental principles of orbital mechanics to spacetravel in the classic book Die Erreichbarkeit derHimmelskörper (The Attainability of CelestialBodies), which was published in 1925. Of par-ticular importance to modern space technologyis Hohmann’s careful enumeration of the mostefficient orbit transfer path between two copla-nar circular orbits. Hohmann demonstrated thatan interplanetary trajectory of minimum energyis an ellipse that is tangent to the orbits of both

planets. This useful principle of orbital mechan-ics is now called the Hohmann transfer orbit (orsometimes the Hohmann transfer ellipse) in hishonor. The technique is not just restricted totraveling between the planets. It is also used toefficiently raise (or lower) the altitude of a space-craft in a circular orbit around a primary celes-tial body, like planet Earth. A simple descriptionof Hohmann’s widely used minimum energy or-bital transfer technique follows below.

Consider a spacecraft in a relatively lowaltitude, circular orbit around Earth or anothercelestial body. The Hohmann transfer orbittechnique raises the spacecraft to a higher alti-tude orbit in the same orbital plane with a min-imum expenditure of energy and propellant.Hohmann’s technique requires two impulsivehigh-thrust burns, or firings, of the spacecraft’sonboard propulsion system. The first burnchanges the original circular orbit to an ellipti-cal one whose perigee is tangent with the lower-altitude circular orbit and whose apogee is tan-gent with the higher-altitude circular orbit.After the spacecraft coasts for half of the ellip-tical transfer orbit (that is, half of the Hohmanntransfer orbit) it reaches a position that is tan-gent with the destination higher-altitude circu-lar orbit. The spacecraft’s propulsion system thenperforms the second high-thrust firing. Whenjust the right amount of thrust is applied, thissecond firing circularizes the spacecraft’s orbit atthe desired new altitude. Hohmann’s techniquecan be used to lower the altitude of a satellitefrom one circular orbit to another circular orbitof less altitude. The main disadvantage withHohmann’s minimum energy orbit transfer ma-neuver is that it takes a great deal of time.

Throughout the late 1920s Hohmann ex-amined the orbital mechanics of interplanetaryspace flight. He actively discussed minimum pro-pellant expenditure, spacecraft design, crewsafety, and maneuver analysis with fellow spacetravel enthusiasts in the German Society forSpace Travel (Verein für Raumschiffahrt, or VFR).

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Hohmann was a well-respected professional en-gineer in service to the city of Essen, so his en-thusiastic participation in the VFR and its spacetravel advocacy served as an important endorse-ment of the society’s interplanetary flightconcepts. His relationship with the VFR was amutually beneficial one. Hohmann found a richfertile environment for his own innovative as-tronautics concepts within the VFR becausesociety membership included such space travelpioneers as Hermann Oberth, WERNHER MAGNUS

VON BRAUN, and Willy Ley (1906–69)—peoplewho quickly recognized the importance ofHohmann’s work.

However, his enthusiasm faded when AdolfHitler (1889–1945) and the Nazi Party seizedpower in 1933. From that point on Hohmannbegan to withdraw from any further Germanrocket or space activity. He did not join manyof his former VFR colleagues as they began todevelop military rockets for the German army,and he did not become a member of Braun’srocket research team at Peenemünde. DespiteHohmann’s desire not to support the military orpolitical objectives of Nazi Germany, the painfulconsequences of World War II nevertheless ad-versely affected him and his family. During thewar, he lost his son Ernst, a soldier. On March11, 1945, exploding Allied bombs claimedHohmann’s life just a week before his 65th birth-day and less than two months before Germanysurrendered. Today, the name of the Hohmanntransfer orbit commemorates his pioneeringwork in orbital mechanics.

5 Hubble, Edwin Powell(1889–1953)AmericanAstronomer, Physicist, Cosmologist

Edwin Powell Hubble is generally credited withcreating the greatest change in the perceptionof the universe since GALILEO GALILEI. It was

Hubble who determined that other galaxies ex-ist outside the Milky Way, and that the universeitself, in fact, was expanding.

Hubble was born on November 20, 1889, inMarshfield, Missouri, the son of Virginia LeeJames Hubble of Virginia City, Nevada, and in-surance broker John Powell Hubble of Missouri.In 1898 his family moved to Chicago, whereHubble excelled at sports at Wheaton HighSchool, setting the state record for the highjump. At the University of Chicago he letteredin track, boxing, and basketball while workingat the school’s Yerkes Observatory in Wisconsin.During this time he worked as a laboratory as-sistant to the renowned Robert Millikan(1868–1953). He earned his B.S. degree inphysics in 1910, then won a Rhodes scholarshipand moved to England to read Roman andEnglish law at Queens College, Oxford.

When he returned to America in 1913,Hubble passed the bar exam and practiced law

The famous American astronomer Edwin Hubbleexamines the interesting features of a spiral galaxy.After carefully investigating many galaxies in the1920s, Hubble announced that the universe wasexpanding—a premise that now forms the basis forall modern observational cosmology. (HaleObservatories, courtesy AIP Emilio Segrè VisualArchives)

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in Louisville, Kentucky, for a year. His heart wasnot in it, however, and in 1914 he returned tothe University of Chicago to study astronomy,earning a Ph.D. in 1917. Just before getting hisdegree, he was invited by GEORGE ELLERY HALE

to join the staff at the famous Mount WilsonObservatory, in Pasadena, California, home ofthe world’s largest telescope at 100 inches. Soon,the United States entered World War I, andHubble’s patriotism came to the fore. Aftercramming for his doctoral degree and taking theoral exams the next morning, he enlisted in theU.S. Army. He was commissioned a captain inthe 343rd Infantry, 86th Division, stationed inFrance, and soon after was promoted to major.After cessation of hostilities, Hubble was mus-tered out of the service in San Francisco and im-mediately headed south to Pasadena, where hepresented himself in his major’s uniform andtook the job offered by Hale.

At the time, the accepted theory was thatthe Milky Way was the boundary of the knownuniverse and that the fuzzy spots of light in thenight sky were simply islands of star clusterswithin that boundary. However, Hubble used theMount Wilson telescope to measure the distanceto the Andromeda Galaxy and determined thatit was 100,000 times farther away from the near-est star than was generally thought, and there-fore had to be its own galaxy. Hubble went onto measure and classify many galaxies, andproved once and for all that the Milky Way isonly one of millions of galaxies in the cosmos.

In what was to become a quantum leap inknowledge of the new field of astrophysics,Hubble then virtually re-created our image ofthe universe by discovering the “redshift” andannouncing to the world in 1929 that the uni-verse was expanding as if it were a gigantic bal-loon. The redshift was determined to be achange in light toward the red end of the spec-trum as galaxies moved away from our own,much like the Doppler effect, which changes thetone of a ringing bell as it is passed in a car or

train. It was this groundbreaking first evidenceof the big bang theory that caused ALBERT

EINSTEIN, who had revised his original calcula-tions of an expanding universe because theywere too “far-fetched,” to revise his theory againand make the statement that it was “the great-est blunder of my life.”

The redshift discovery propelled Hubble tothe highest ranks of worldwide astronomers andearned him unexpected celebrity. He becameclose friends with several prominent movie starsand scientists, and was called by Time magazinethe “toast of Hollywood.” In 1924 Hubble hadmarried Grace Burke, and the couple traveledthe world and were honored guests at lavishHollywod parties during the 1930s and 1940s.When World War II broke out, Hubble wantedto enlist again but became convinced that hisscientific knowledge would do the country moregood in research on the home front. He ulti-mately was awarded a Medal of Merit for his bal-listics work at the Aberdeen Proving Ground’sultrasonic wind tunnel testing grounds in NewMexico.

After the war, Hubble was instrumental inbuilding the 200-inch Hale telescope at MountPalomar, California, and was given the highhonor of being the first person to use it. He con-tinued his research at Mount Palomar until hisdeath in Pasadena of a cerebral thrombosis onSeptember 28, 1953.

In his distinguished career as one of the 20thcentury’s greatest astronomers, Hubble inventedthe science of cosmology and completely changedour vision of the universe. His verification of theBig Bang theory has caused scientists and the-ologians alike to debate the tremendous size ofthe cosmos and to theorize about what it wasthat “banged” in the first place.

Such was Hubble’s fame and impact on as-tronomy and cosmology that his name is at-tached to several parameters and formulae suchas Hubble’s Law, the Hubble Sequence, Hubble’sZone of Avoidance, the Hubble Galaxy type, the

172 Huggins, Sir William

Hubble Luminosity Law, the Hubble Red-ShiftDistance Relation, the Hubble Radius, as well asthe Hubble crater on the Moon, and the HubbleSpace Telescope.

5 Huggins, Sir William(1824–1910)BritishAstronomer, Spectroscopist

Sir William Huggins, a skilled amateur astro-nomer and spectroscopist, helped to revolution-ize observational astronomy in the 19th century.Using a private astronomical observatory that hebuilt just outside London, he performed pio-neering spectral measurements of the stars andthen compared the observed stellar spectra tochemical spectra generated in his laboratory onEarth. In 1868 Huggins profoundly influencedthe future direction of cosmology when he at-tempted to measure a star’s radial velocity by us-ing the Doppler shift in its spectrum. QueenVictoria knighted him, and he copublished amajor work on stellar spectra in 1899 withhis talented young wife, Lady Margaret MurrayHuggins.

Huggins was born in London, England, onFebruary 7, 1824. His father was a prosperousmerchant, so he provided his son not only a highquality private education but also an importantdegree of financial independence. Under suchfortunate circumstances, Huggins became one ofGreat Britain’s most successful and competentprivate (amateur) astronomers. Throughout hislifetime, he was able to contribute productivelyto astronomy without having a formal attach-ment to either a university or an establishedobservatory. Huggins received his earliest edu-cation in the City of London School, but laterlearned mathematics, the physical sciences, andseveral languages at home from private teachers.At 18 years of age, he passed up a formal collegeeducation to take over the family business when

his father became seriously ill. For more than adecade, Huggins conducted business by day andastronomy at night. He enjoyed both astronomyand microscopy, since both of these disciplinesgave him an opportunity to pursue original in-vestigations.

When he was 30, Huggins sold the familybusiness and dedicated the rest of his life to as-tronomy. To support this decision, he moved toan open region called Upper Tulse Hill, south ofLondon, in 1856 and constructed a large privateobservatory adjacent to his new house. In 1858he added a high-quality 8-inch refractor tele-scope, manufactured by the world-famousAmerican optician ALVAN GRAHAM CLARK.

In January 1862 Huggins began a productivecollaboration with W. Allen Miller, a professorof chemistry at King’s College in London.Huggins wanted to apply to the Kirchhoff-Bunsen solar spectroscopy experiment to lightfrom the distant stars, but he recognized that thiswas a challenging effort and that Miller’s expe-rience in chemical spectroscopy would prove in-valuable. However, Miller himself was initiallydoubtful that Huggins would be successful in de-veloping stellar spectroscopy. For one thing, theamount of starlight collected by telescope andavailable for spectral analysis would be only avery tiny fraction (on the order of millionths tobillionths) of the amount of sunlight availableto Kirchhoff and Bunsen when they solved themystery of the Fraunhofer lines.

Despite Miller’s initial misgivings, one of thegreat milestones in astronomical spectroscopytook place in 1864 when Huggins announcedthat the distant stars were composed of the samechemical elements as the Sun. With Miller as acoauthor, Huggins published a piece entitled“On the Lines of Some Fixed Stars,” in thePhilosophical Transactions of the Royal Society.This paper included diagrams of the spectra ofstars, such as Sirius, Betelgeuse, and Vega. In onebrilliant stroke, spectroscopy became the bridgelinking terrestrial chemistry to the chemistry of

Huggins, Sir William 173

the “unreachable” stars. Unknown to Huggins,the Italian astronomer PIETRO ANGELO SECCHI

in Rome and others were beginning to conductsimilarly important efforts in astronomical spec-troscopy. This particular effort earned Hugginsand Miller the 1867 Gold Medal from the RoyalAstronomical Society.

Prior to publishing this work, Huggins alsoattempted to obtain photographs of the spectra ofSirius and Capella in February 1863, but his ef-forts were greatly limited by contemporary pho-tographic technology. About a decade later, newphotographic materials became available andgreatly improved the amateur astronomer’s abil-ity to make useful photographic records of stellarspectra.

Huggins orchestrated another great momentin observational astronomy in August 1864 byturning his stellar spectroscope to study the fuzzycelestial objects called nebulas. At the time, as-tronomers were generally divided concerningthe exact nature of nebulas. Some hypothesizedthat they were great gaseous clouds, while oth-ers considered them to be enormous collectionsof stars too distant to be individually resolved bya telescope.

On the evening of August 29, Huggins ob-served a single bright line in the spectrum of anebula in the constellation Draco and immedi-ately concluded that it was a giant cloud ofluminous gas. Later, he found a few bright emis-sion lines in certain other nebulas, including thegreat nebula in Orion. Huggins also correctlynoted that certain spiral nebulas, like Messier 31in Andromeda, showed continuous spectra andmust be composed of numerous unresolved stars.As a historic note, many of these distant spiralnebulas did indeed turn out to be enormous col-lections of stars—that is, other galaxies, or is-land universes, as originally suggested by Kantand Laplace. However, that particular astro-nomical knowledge would not clearly emergeuntil decades later, in the early part of the 20thcentury.

While solving one nebula mystery, Hugginscreated another that would remain unresolved forabout 60 years. In 1866 he observed the spectraof certain nebulas and discovered previouslyunidentified bright emission lines that he decidedto attribute to a new element that he called “neb-ulium.” It was not until 1927 that the Americanastrophysicist Ira Sprague Bowen (1898–1973)properly explained this puzzling phenomenon.The bright emission lines did not belong to anynew element; rather, Bowen’s detailed investiga-tion revealed that the mysterious green lines wereactually special (forbidden) transitions of the ion-ized gases oxygen and nitrogen. In 1866 the RoyalSociety presented Huggins with its highest award,the Royal Medal, for his research involving as-tronomical spectroscopy.

During the 1860s Huggins also helpedchange the direction of modern cosmology whenhe attempted to measure the radial velocity ofSirius by detecting any Doppler shift in its spec-trum. He used his relatively imprecise spectralmeasurements (acquired without the aid of pre-cision spectral photography) to conclude thatthere was a redshift in the spectrum of Sirius ofsufficient magnitude to suggest that this star wasreceding from the solar system at about 47 kilo-meters per second. He described this work in apaper, “On the Spectra of the Fixed Stars,” thatwas coauthored with Miller and belatedly pub-lished in 1868 in Philosophical Transactions of theRoyal Society.

Although this value of radial velocity wasnot close to the value obtained later, Hugginsprovided the pioneering concept that encour-aged other astronomers, such as EDWIN POWELL

HUBBLE, to use the Doppler effect (redshift) inthe spectra of distant galaxies. Using this ap-proach, Hubble was eventually able to postulatethe cosmological model of an expandinguniverse. The radial velocity of a star is simplyits motion toward (considered negative) oraway from (considered positive) the solar sys-tem. Contemporary astronomical measurements

174 Huggins, Sir William

show the star Sirius has radial velocity of 28kilometers per second, meaning it is actually ap-proaching the solar system.

On May 18, 1866, Huggins became the firstastronomer to observe the spectrum of a nova(Nova Coronae 1866), detecting its brighthydrogen emission lines. He also applied astro-nomical spectroscopy to comets. In 1868 he ob-served the spectrum of a comet and reported thepresence of luminous carbon gases. He marriedMargaret Lindsay Murray in 1875 and she im-mediately became not only a loving wife but alsoa most talented collaborator. As he aged, LadyMargaret Huggins, being 24 years younger thanher husband, did more and more of the actualobserving. In 1899 Lord and Lady Huggins pub-lished their award-winning Atlas of RepresentativeStellar Spectra. He was knighted by QueenVictoria in 1897 and served as president of theRoyal Society from 1900 to 1905. Sir WilliamHuggins died in London on May 12, 1910.

Despite his lack of formal schooling, hisepochal astronomical work brought Huggins fullrecognition from learned societies and universi-ties. He was elected as a member to the RoyalSociety in 1865 and received several of its pres-tigious medals, including the Royal Medal(1866), the Rumford Medal (1880), and theCopley Medal (1898). The Royal AstronomicalSociety gave him its distinguished Gold Medaltwice, in 1867 and again in 1885. The FrenchAcademy of Sciences presented him its LalandeGold Medal (1872), the Valz Prize (1883), andthe Janssen Gold Medal (1888). Finally, the U.S.National Academy of Sciences awarded him itsHenry Draper Medal in 1901. Perhaps the great-est contribution that this wealthy British ama-teur astronomer made to the development ofastronomical spectroscopy was his pioneering ef-fort to interpret stellar observations by usingcarefully prepared laboratory observations ofchemical spectra.

175

J5 Jeans, Sir James Hopwood

(1877–1946)BritishAstronomer, Mathematician, Physicist

At the dawn of 20th-century astronomy, Sir JamesHopwood Jeans proposed the controversial andnow generally ignored tidal theory to explain theorigin of the solar system. In 1928 he made an-other bold suggestion that matter was beingcontinuously created in the universe. This con-troversial hypothesis led other scientists to estab-lish a steady-state universe model in cosmology.Big Bang cosmology has now all but eliminatedthe steady-state model that traces its origins tohis initial speculations. Following his knighthoodin 1928, he focused much of his creative activityon writing popular books about astronomy.

Jeans was born in Ormskirk, Lancashire,England, on September 11, 1877, but his familymoved to London when he was three years old.He was the son of a journalist and this proba-bly influenced his strong inclination towardwriting during childhood. Jeans enrolled at TrinityCollege, Cambridge University, in October 1896.He received a degree in mathematics in 1900and became a Fellow of Trinity College in 1901.During this period, he was very active, publish-ing research on a variety of topics in appliedmathematics, astronomy, and physics. He was

particularly interested in the kinetic theory andthermodynamic behavior of gases, and publishedhis first major textbook, The Dynamical Theoryof Gasses, in 1904, while recuperating from about with tuberculosis.

Jeans began his career as a mathematician,but made important contributions in such di-verse fields as molecular physics, astrophysics,and cosmology. In 1904 he became a lecturer inmathematics at Cambridge University, then in1905 traveled to the United States to serve as aprofessor of applied mathematics at PrincetonUniversity in New Jersey until 1909. While atPrinceton he published his second major text-book, Theoretical Mechanics, in 1906. He becamea Fellow in the British Royal Society in 1907and also married an American, Charlotte TiffanyMitchell, a member of the famous Tiffany fam-ily from New York. Jeans published anotherbook, The Mathematical Theory of Electricity andMagnetism, in 1908. Later the next year he re-turned to Great Britain and accepted an ap-pointment as the Stokes Lecturer in appliedmathematics at Cambridge University. However,he kept this position only until 1912, beforedevoting himself entirely to technical writingand research in applied mathematics, especiallyas related to astronomy and cosmology.

In 1917 Jeans won the Adams Prize fromCambridge University for an essay titled

176 Jeans, Sir James Hopwood

“Problems of Cosmogony and Stellar Dynamics”which was published two years later as a book.In this work Jeans mathematically addressedthe stability of a rotating mass and then tookdirect issue with the nebular hypothesis of Kantand Laplace as the basis for the formation ofthe planets. He endorsed, instead, a tidal (orcatastrophic) theory to explain the formationof the solar system. This interesting theory sug-gests that a rogue star passed close to the Sunbillions of years ago and gravitationally tuggeda cigar-shaped wedge of matter out of the Sunthat eventually condensed into the planets. Formore than a decade the tidal theory remainedpopular in 20th-century astronomy. This the-ory implied, however, that planetary systemswould be rare because their formation woulddepend on catastrophic encounters of passingrogue stars. By the mid-1940s, revitalized ver-sions of the nebular hypothesis emerged anddisplaced tidal theory from its position of dom-inance in astrophysics. This took place becauseastronomers once again regarded planet for-mation as a common, normal part of stellarevolution. The recent discovery of extra solarplanets provides compelling observational evi-dence in support of the refined nebular hypoth-esis and justifying the abandonment of the tidalhypothesis.

By 1917 his excessively high workload be-gan to stress his heart and adversely influencehis health. Therefore, in 1918 Jeans moved hisfamily to more relaxed surroundings in Dorking,Surrey, a place where he could devote more timeto recreation and music, while still pursuingtechnical writing at a less hectic pace. However,his interest in astronomy and cosmology also en-couraged him to undertake research at the MountWilson Observatory, in Pasadena, California, andJeans enjoyed an extended appointment thereas a research associate from 1923 to 1944. Thisposition exposed him to stimulating new ideasin astronomy and gave him the opportunity topersonally interact with many notable American

scientists, including Walter Sydney Adams andARTHUR HOLLY COMPTON.

In 1928 Jeans suggested in his book Astronomyand Cosmogony that matter was being continu-ally created in the universe. This interestingconjecture became the foundation of the steady-state theory of cosmology—a theory champi-oned by some scientists in the 1940s and 1950sin opposition to Big Bang cosmology. Today,steady-state cosmology has been displaced bythe general acceptance of an expandinguniverse cosmology based on the Big Banghypothesis.

Jeans was elevated to knighthood in 1928,and starting in 1929 he focused his diverse in-tellectual talents on writing books that greatlypopularized astronomy and science. His mostfamous popular books include: The Universearound Us (1929), The Mysterious Universe (1930),The New Background of Science (1933), ThroughSpace and Time (1934), and Physics and Philosophy(1943).

Jeans received numerous honors and awards.He received the Gold Medal from the RoyalAstronomical Society in 1922 and the FranklinMedal in 1931. He served as the president ofthe Royal Astronomical Society from 1925 to1927 and as the president of the BritishAssociation for the Advancement of Science in1934. He was also awarded the Order of Meritin 1939.

When his first wife died in 1934, Jeans re-married a year later. His second wife, SuzanneHock, came from Vienna, Austria, and was anaccomplished musician. Their common interestin music served as the source of inspiration forJeans’s popular book Science and Music (1938).Jeans died at home in Dorking, England, onSeptember 16, 1946, due to heart failure. Hisnumerous publications and bold hypotheses notonly helped shape astrophysics and cosmologyin the first half of the 20th century but alsomade astronomy familiar and popular to manyless-technical readers.

Jones, Sir Harold Spencer 177

5 Jones, Sir Harold Spencer(Spencer Jones)(1890–1960)BritishAstronomer

Sir Harold Spencer Jones was a multitalentedindividual who used the close passage of theasteroid Eros 433 in 1931 to achieve precisemeasurements of an important astronomer’s“yardstick,” the astronomical unit (AU)—thatis, the average distance from the Earth to theSun. From 1933 to 1955 he served Great Britainas the 10th Astronomer Royal. He also wrote anumber of books that popularized astronomy, in-cluding the pioneering work Life on Other Worlds(1940) which opened up all manner of interest-ing speculations in the exciting field now knownas exobiology.

Jones was born in London on March 29,1890. The son of an accountant, he receivedhis early education at Latymer Upper Schooland then attended Jesus College at CambridgeUniversity on a scholarship. Following a distin-guished undergraduate career, he earned his de-gree in mathematics in 1911 and in physics in1912. In 1913 Jones became the chief assistantat the Royal Greenwich Observatory. Except forWorld War I service with the British Ministry ofMunitions, he would hold this position atGreenwich until 1923. He was elected a Fellowof Jesus College in 1914. He married GladysMary Owens in 1918 and the couple had twosons. In 1923 he replaced Sir Frank Dyson as theRoyal Astronomer at the Cape of Good HopeObservatory in South Africa.

In 1928, as Royal Astronomer at the Capeof Good Hope Observatory, Jones took chargeof a cooperative international project under thesponsorship of the International AstronomicalUnion (IAU) to refine estimates of the astro-nomical unit using positional data for the aster-oid Eros 433. Following a suggestion originallymade by JOHANN GOTTFRIED GALLE, Jones led a

worldwide effort to refine the estimate of thedistance from the Earth to the Sun by triangu-lating the distance of Eros 433 as it approachedclose to Earth in 1931. Eros 433 was discoveredin 1898 and visited by a NASA spacecraft in2000. A member of the Mars-crossing Amorgroup, it is an irregularly shaped minor planet,approximately 33 × 13 × 13 kilometers in sizeand resembling a fat banana. In 1931 it camewithin 26 million kilometers of Earth, and as-tronomers at observatories all over the worldphotographed the celestial object and recordedaccurate data concerning its position. Jonesgathered these data and then spent the nextdecade reviewing more than 3,000 photographsand making extensive calculations in a tremen-dous effort to refine the estimate of solar paral-lax—that is, the angle subtended by Earth’s ra-dius when viewed from the center of the Sun.Not until the early 1940s, while World War IIwas raging, did Jones, now back in Greenwichas Astronomer Royal, finally announce his re-fined value for solar parallax as 8.790 6 0.001arc seconds. Because of the global conflict, muchof the significance of his great personal effort es-caped the immediate attention of the interna-tional astronomical community. Today, the IAUdefines solar parallax as 8.794148 arc seconds,based on radar measurements.

He left South Africa and returned to GreatBritain in 1933 to continue his tenure asAstronomer Royal. In addition to refining solarparallax, Jones made a second major contribu-tion to astronomy by using more accurate quartzclocks to study subtle anomalies in Earth’s ro-tation rate. In 1939 he announced that hismeasurements indicated that Earth did not ro-tate regularly, but rather kept time “like an in-expensive clock.” Specifically, his measurementsindicated that, with respect to other solar sys-tem bodies, Earth was rotating slowly by abouta second per year—an amount sufficient to ac-count for some of the tiny anomalies recorded inlunar or planetary ephemerides. This work was

178 Jones, Sir Harold Spencer

instrumental in the introduction of ephemeristime in 1958.

After World War II, Jones supervised theplans and activities involved in moving the RoyalObservatory from Greenwich to HerstmonceuxCastle, in Sussex. Urban light and chemicalpollution, detrimental by-products of London’sgrowth, necessitated this change in location.Jones retired in 1955 with the relocation wellunderway. By 1958 the move of the RoyalObservatory to its new location was successfullycompleted.

While serving as Astronomer Royal, Jonescommunicated the excitement and wonder ofastronomy to both technical and nontechnicalreaders alike by writing such interesting books

as Worlds without End (1935), Life on OtherWorlds (1940), and A Picture of the Universe(1947). He received many honors for his con-tributions to astronomy. In 1930 he became aFellow of the Royal Society of London. He wasknighted by King George VI in 1943. He alsoreceived the Royal Medal of the British RoyalSociety (1919), the Gold Medal of the RoyalAstronomical Society (1943), and the BruceGold Medal of the Astronomical Society of thePacific (1949). As a lasting tribute to his life-long service to Great Britain and to the astro-nomical sciences, Jones was elevated to the rankof Knight of the British Empire in 1955 byQueen Elizabeth II. He died at age 70 onNovember 3, 1960, in London.

179

K5 Kant, Immanuel

(1724–1804)GermanNatural Philosopher, Astronomer

The great German philosopher Immanuel Kantwas the first to propose the nebula hypothesis, aconcept he introduced in his 1755 book, GeneralHistory of Nature and Theory of the Heavens. Inthis hypothesis, Kant anticipated modern astro-physics when he suggested that the solar systemformed out of a primordial cloud of interstellarmatter. Kant also introduced the term island uni-verses to describe the distant collections of starsthat astronomers now call galaxies. He was a trulybrilliant thinker, and his works in metaphysicsand philosophy exerted great influence on Westernthinking far beyond the 18th century.

Kant was born on April 22, 1724, inKönigsberg, East Prussia (now Kaliningrad,Russia). He lived a very orderly and organizedlife, so precise that his neighbors would set theirwatches by his behavior. Although he was a bril-liant, popular conversationalist, during his en-tire lifetime Kant never ventured more thanabout 100 kilometers from his birthplace. His fa-ther was a poor, but well-respected, saddler, andhis mother created a home environment filledwith a strict adherence to Protestantism. At age16 Kant enrolled at the University of Königsberg,

where he studied philosophy, mathematics, andnatural philosophy (physics). He also attendedclasses in theology. When his father died in1745, Kant found himself in financial difficul-ties and served as a private tutor for nine yearsto earn enough money to finish his studies. In1755 he finally completed the requirements forhis degree at the University of Königsberg andpublished General History of Nature and Theoryof the Heavens (Allgemeine naturgeschichte undtheorie des himmels) presenting his view of thephysical universe. In this book Kant adheredstrictly to the principle of mechanical causation(using Newtonian principles) and avoided theprobing metaphysical speculations that wouldlater characterize his great works in philosophy.

Although Kant is primarily regarded as agreat philosopher and not an astronomer orphysicist, his early work addressed Newtoniancosmology and contained several important con-cepts that, amazingly, anticipated future devel-opments in astronomy and astrophysics. First,Theory of the Heavens introduced the nebular hy-pothesis of the formation of the solar system:namely, that the planets formed from a cloud ofprimordial interstellar material that slowly col-lected and began swirling around a protosununder the influence of gravitational attractionand eventually portions of this rotating disccondensed into individual planetary “clumps.”

180 Kapteyn, Jacobus Cornelius

Laplace independently introduced a similarversion of Kant’s nebular hypothesis in 1796.Second, Kant suggested that the Milky WayGalaxy was a lens-shaped collection of manystars that orbited around a common center, sim-ilar to the way the rings of Saturn orbited aroundthe gaseous giant planet. Third, he speculatedthat certain distant spiral nebulas were actuallyother “island universes”—a term he coined todescribe the modern concept of other galaxies.Fourth, Kant suggested that tidal friction wasslowing down Earth’s rotation just a bit—a boldscientific speculation confirmed by precise meas-urements in the 20th century. Finally, he alsosuggested the tides on Earth are caused by theMoon and that this action is responsible for thefact the Moon is locked in a synchronous orbitaround Earth, always keeping the same “face”(called the nearside) presented to observers onEarth. Not too bad, for a person who had justcompleted his university degree and was aboutto embark on a long and productive academiccareer best known for its important philosophi-cal contributions to Western civilization.

Upon graduating from the University ofKönigsberg, Kant became a lecturer (Privatdozent)at the university and served in that capacity forthe next 15 years. During that time, his fame asa brilliant thinker and wonderful teacher grew.In 1770 university officials appointed him to thechair of logic and metaphysics. This promotionmarked the beginning of a period in which Kantwrote a powerful series of books that shapedWestern thinking for the next two centuries.The most important of these works was hisCritique of Pure Reason (Kritik der reinenVernunft)—a treatise on metaphysics that is re-garded as a classic contribution to philosophy.A full and detailed discussion of Kant’s othergreat works in metaphysics, ethics, judgment,and reason is well beyond the scope of thisbook.

Although Kant never married and did notventure far from home, he was not a recluse.

On the contrary, he was a brilliant conversa-tionalist and excellent teacher, who enjoyed awide circle of friends who constantly sought hisviews on contemporary intellectual and politi-cal issues. He retired from the university in 1796and died on February 12, 1804, in Königsberg.

5 Kapteyn, Jacobus Cornelius(1851–1922)DutchAstronomer

Toward the end of the 19th century, JacobusKapteyn made significant contributions to theemerging new field of astrophotography—thatis, taking analysis-quality photographs of celes-tial objects. He also pioneered the use of statis-tical methods to evaluate stellar distributionsand the radial and proper motions of stars.Between 1886 and 1900, Kapteyn carefully scru-tinized numerous photographic plates collectedby SIR DAVID GILL at the Cape of Good HopeRoyal Observatory, in South Africa. He thenpublished these data as a three-volume catalogthat contained the positions and photographicmagnitudes of more than 450,000 SouthernHemisphere stars.

Kapteyn was born on January 19, 1851, atBarneveld in the Netherlands. From 1869 to1875, he studied physics at the University ofUtrecht. After graduating with his doctorate,Kapteyn accepted a position as a member of theobserving staff at the Leiden Observatory.During his studies, he had not given any specialattention to astronomy, but this employmentopportunity convinced him that studying stel-lar populations and the structure of the universewas how he wanted to spend his professionallife.

In 1878 Kapteyn received an appointmentas the chair of astronomy and theoretical me-chanics at the University of Groningen. Sincethe university did not have its own observatory,

Kapteyn, Jacobus Cornelius 181

Kapteyn decided to establish a special astro-nomical center dedicated to the detailed analy-sis of photographic data collected by otherastronomers. The year following this bril-liant career maneuver, he married CatharinaKarlshoven, with whom he had three children.In the mid-1880s Kapteyn interacted with SirDavid Gill, Royal Astronomer at the Cape ofGood Hope Observatory. The two astronomersdeveloped a cordial relationship and Kapteynvolunteered to make an extensive catalog of the stars in the Southern Hemisphere, us-ing the photographs taken by Gill at the CapeObservatory.

In 1886 Kapteyn’s collaboration with Gillbegan. Underestimating the true immensity ofthe task for which he had just volunteered,Kapteyn worked for more than a decade in twosmall rooms at the University of Groningen.During his labor-intensive personal crusade inphotographic plate analysis, he enjoyed supportfrom just one permanent assistant, several part-time assistants, and occasional convict laborfrom the local prison.

The end product of Kapteyn’s massivepersonal effort was the Annals of the CapeObservatory—an immense three-volume workpublished between 1896 and 1900 that con-tained the position and photographic magni-tudes of 454,875 Southern Hemisphere stars. Hispioneering effort led to the creation of theAstronomical Laboratory at the University ofGroningen, and the establishment of the highlyproductive Dutch school of 20th-century as-tronomers.

In 1904 Kapteyn noticed that the propermotion of the stars in the Sun’s neighborhooddid not occur randomly, but rather moved in twodifferent, opposite streams. However, he did notrecognize the full significance of his discovery.Years later, one of his students, JAN HENDRIK

OORT, demonstrated that the star-streaming phe-nomenon first detected by Kapteyn was observa-tional evidence that the Galaxy was rotating.

Along with statistical astronomy, Kapteynwas interested in the general structure of theGalaxy. In 1906 he attempted to organize a co-operative international effort in which as-tronomers would determine the population ofstars of differing magnitude in 200 selected ar-eas of the sky and also measure their radial ve-locities and proper motions. The radial velocityof a star is a measure of its velocity along theline of sight with Earth. Astronomers use theDoppler shift of a star’s spectrum to indicatewhether it is approaching Earth (blueshiftedspectrum) or receding from Earth (redshiftedspectrum). The proper motion of a star is thegradual change in the position of a star due toits motion relative to the Sun. The proper mo-tion (symbol µ) is the apparent angular motionper year of a star as observed on the celestialsphere—that is, the change in its position in adirection that is perpendicular to the line of sight.

Kapteyn gathered enormous quantities ofdata, but World War I interrupted this multi-national cooperative effort. Nevertheless, heexamined the data that was collected but over-looked the starlight-absorbing impact of inter-stellar dust. So, in the tradition of SIR WILLIAM

HERSCHEL, he postulated that the Milky Waymust be lens-shaped, with the Sun locatedclose to its center. The American astronomerHARLOW SHAPLEY disagreed with the Dutchastronomer’s erroneous model and, in 1918,conclusively demonstrated that the Galaxy wasfar larger than Kapteyn had estimated and thatthe Sun actually resided far away from thegalactic center.

Kapteyn’s model of the Galaxy suffered whenapplied to the galactic plane because he lackedsufficient knowledge about the consequences ofinterstellar absorption, not because he was care-less in his evaluation of observational data. Onthe contrary, he was a very skilled and carefulanalyst who helped found the important field ofstatistical astronomy. He died in Amsterdam,the Netherlands, on June 18, 1922. During his

182 Kepler, Johannes

lifetime he received many international awardsand medals, including the Gold Medal of the Royal Astronomical Society of London in1902, the Watson Medal from the AmericanAcademy of Sciences in 1913, and the BruceGold Medal from the Astronomical Society of the Pacific, also awarded in 1913. Perhapshis greatest overall contribution to astronom-ical sciences was the creation of the Dutchschool of astronomy, which provided manygreat astronomers who continued his legacy ofexcellence in data analysis throughout the20th century.

5 Kepler, Johannes (Johann Kepler)(1571–1630)GermanAstronomer, Mathematician

Johannes Kepler was a brilliant contemporary ofGALILEO GALILEI who helped start the ScientificRevolution. While Galileo’s pioneering use ofthe telescope provided the observational foun-dations for Copernican cosmology, Kepler’sinnovative mathematical contributions to as-tronomy provided the theoretical foundations.Through painstaking and arduous analyses,Kepler developed his three laws of planetarymotion—important physical principles that de-scribe the elliptical of orbits of planets aroundthe Sun. His work not only provided the em-pirical basis for the early acceptance of NICOLAS

COPERNICUS’s heliocentric hypothesis but alsothe mathematical starting point from which SIR

ISAAC NEWTON developed his law of gravitation.Kepler gave astronomy its modern, mathematicalfoundation.

Kepler was born on December 27, 1571, inthe small town of Weil der Stadt, Württemberg,Germany (then part of the Holy RomanEmpire). His father was a mercenary soldier andhis mother was the daughter of an innkeeper. Asickly child, Kepler suffered from smallpox at the

age of three. The disease impaired the use of hishands and affected his eyesight for the remain-der of his life. When Kepler was five, his fatherleft to fight in one of the many local conflictsravaging Europe at the time, and he never re-turned home. So Kepler spent the remainder ofhis childhood living with his mother at hisgrandfather’s inn.

As a child, his mother took him outside thewalls of the city so he could witness the greatcomet of 1577. This special event appears to haveencouraged his lifelong interest in astronomy.

Johannes Kepler combined painstaking and arduousanalyses with simple mathematics to describe theelliptical movement of the known planets around theSun. With his famous three laws of planetary motion,Kepler established the mathematical foundations forheliocentric (Copernican) cosmology. His work notonly provided the empirical basis for the earlyacceptance of the heliocentric hypothesis, it alsoprovided the mathematical starting point from whichSir Isaac Newton could develop his law of gravitation.(AIP Emilio Segrè Visual Archives)

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After completing local schooling, he pursued areligious education at the University of Tübingenin the hopes of becoming a Lutheran minister.He graduated in 1588 with his baccalaureate de-gree and then went on to complete a master’sdegree in 1591.

While Kepler was a student at the Uni-versity of Tübingen, his professor of astronomy,Michael Maestlin (1550–1632) introduced himto the Copernican hypothesis. Kepler immedi-ately embraced the new heliocentric model ofthe solar system. As his interest in the motionof the planets grew, Kepler’s skill in mathemat-ics also emerged. By 1594 partially because healienated church officials after expressing hispersonal disagreement with certain aspects ofLutheran doctrine, he totally abandoned anyplans for the Lutheran ministry and became amathematics instructor in Gratz (Graz), Austria.

As well as an accomplished astronomer andmathematician, Kepler also maintained a stronginterest in mysticism throughout his life. He ex-tracted many of his mystical notions from theearly Greeks, including the “music of the celes-tial spheres” that was originally suggested byPythagoras in the sixth century B.C.E. As wascommon for many 17th-century astronomers,Kepler also dabbled in astrology. He often casthoroscopes for important benefactors, such asEmperor Rudolf II (1552–1612) and Duke(Imperial General) Albrecht von Wallenstein.Astrology provided the frequently impoverishedKepler with a supplemental source of income.His well-prepared horoscopes also earned Keplerthe political protection of many satisfied high-ranking officials in the Holy Roman Empire. Asa result, he was often the only prominentProtestant allowed to live in a German cityunder control of a Catholic ruler.

In 1596 Kepler published Mysterium Cos-mographicum (The cosmographic mystery)—anintriguing work in which he unsuccessfullytried to analytically relate PLATO’s five basic geo-metric solids (as found in early Greek phi-

losophy and mathematics) to the distances of thesix known planets from the Sun. This work, of-ten considered the first outspoken defense of theCopernican hypothesis, also attracted the at-tention of TYCHO BRAHE, the most famous(pretelescope) astronomer of the period.

Kepler married his first wife in 1597. Shewas a wealthy widow named Barbara Mueller.However, when all the Protestants were forcedto leave the Catholic-controlled city of Gratzin 1598, Kepler found it extremely difficult toliquidate her property holdings. Any nuptialfinancial comfort quickly dissipated, as theKepler family hastily departed Gratz and movedto Prague in response to Brahe’s invitation.

Kepler joined the elderly Danish astronomerin 1600 as his assistant. When Brahe died thefollowing year, Kepler succeeded him as theimperial mathematician to the Holy RomanEmperor Rudolf II. As a result, Kepler acquiredall the precise astronomical data Brahe had col-lected. These data, especially Brahe’s preciseobservations of the motion of Mars, played animportant role in the development of Kepler’sfamous three laws of planetary motion.

In 1604 Kepler wrote the book De StellaNova (The new star), in which he described abright new star (now known as a supernova) inthe constellation Ophiuchus. He first observedthe event on October 9, 1604. Modern as-tronomers sometimes refer to this supernovaevent, the remnants of which form radio source3C 358, as Kepler’s Star. According to early17th-century astronomical observations thattook place in Europe and Korea, this particularsupernova remained visible for approximatelyone year.

From 1604 until 1609 Kepler’s main interestwas a detailed study of the orbital motion of Mars.Before his death, Brahe had challenged his youngassistant with the task of explaining the puzzlingmotion of the Red Planet. Even accepting theCopernican hypothesis, which Kepler did butBrahe did not, a circular orbit around the Sun

184 Kepler, Johannes

The year 1611 proved extremely difficult forKepler in that his first wife, Barbara, and theirseven-year-old son died. Then his royal patron,Emperor Rudolf II, abdicated the throne in fa-vor of his brother Matthias. Unlike his brotherRudolf, Matthias did not believe in tolerance forthe Protestants living in his realm. So Kepler,along with many other Lutherans, left Prague toavoid the start of an impending civil war be-tween Catholics and Protestants. After buryinghis wife and son together, he moved his surviv-ing children to Linz, where he accepted a posi-tion as district mathematician and teacher.

In 1613, desperately needing someone tocare for his children, he married SusannaReuttinger, herself an orphan. Although his sec-ond marriage was a generally happy one, Keplercontinued to suffer from misfortune. He hadchronic financial troubles, experienced thedeaths of two infant daughters, and had to re-turn to Württemberg to defend his mother,Katharina Kepler, who was being put on trial asa witch. This trial dragged on for three years andKepler used all his legal wit and political capi-tal to get her released. Her torture and death atthe stake were the very likely outcomes thatKepler struggled so hard to prevent. Despitethese personally draining problems, he remaineda diligent mathematician in Linz until 1628 andused his available time to write several books.He moved his family in 1628 to Sagan (inSilesia) in order to work for the Imperial generalAlbrecht von Wallenstein (1583–1632) as hiscourt mathematician. With the Thirty Years’War (1618–48) raging in Germany, in 1630 hehad to flee Sagan to avoid religious persecutionas Wallenstein fell from power.

When he published De Harmonica Mundi(Concerning the harmonies of the world) in1619, Kepler continued his great work involvingthe orbital dynamics of the planets. Althoughthis book extensively reflected Kepler’s fascina-tion with mysticism, it also provided a very sig-nificant insight that connected the mean dis-

did not properly fit Brahe’s carefully observedorbital position data. With youthful optimism,Kepler told the older astronomer he would havean answer for him in a week, but it took Keplereight long and hard years to finally obtain thesolution. The movement of Mars could not beexplained and predicted unless Kepler assumedthe orbit was an ellipse with the Sun located atone focus. This revolutionary assumption pro-duced a major advance in solar system astronomyand provided the first empirical evidence of thevalidity of the Copernican model.

Kepler recognized that the other observ-able planets also followed elliptical orbitsaround the Sun. He published this importantdiscovery in 1609 in the book Astronomia Nova(New astronomy). The book, dedicated toEmperor Rudolf II, confirmed the Copernicanmodel and permanently shattered 2,000 yearsof geocentric Greek astronomy. Kepler becamethe first scientist to present a well-writtendemonstration of the scientific method. Thiswork clearly acknowledged the errors and im-perfections in the observational data and thencompensated for these inaccuracies by creatinga new scientific law (model) that used mathe-matics to accurately predict the natural phe-nomenon of interest (here the orbital positionof Mars). In this important document, Keplerannounced that the orbits of the planets are el-lipses with the Sun as a common focus. Today,astronomers call this statement Kepler’s FirstLaw of Planetary Motion. Kepler also intro-duced his Second Law of Planetary Motion inthis book.

German church officials (Lutheran or Cath-olic) never officially attacked Kepler for advo-cating the Copernican hypothesis. This wasprobably due to his powerful political benefac-tors. However, the same benign neglect did notbefall his fiery Italian contemporary, Galileo,who shared the same passion for the Copernicanhypothesis and corresponded with Kepler regu-larly until about 1610.

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tances of the planets from the Sun with their or-bital periods. This discovery became known asKepler’s Third Law of Planetary Motion.

Between 1618 and 1621, despite constantrelocations Kepler summarized all of his plane-tary studies in an important seven-volume ef-fort entitled Epitome Astronomica Copernicanae(Epitome of Copernican astronomy). This workpresents all of Kepler’s heliocentric astronomy ina systematic way. As a point of scientific history,Kepler actually based his second law (the law ofequal areas) on the mistaken (but reasonable forthe time) physical assumption that the Sun ex-erted a strong magnetic influence on all theplanets. Later in the 17th century, Newton pro-vided the right physical explanation when hedeveloped the universal law of gravitation toidentify the force that causes the planetary mo-tion so correctly described by Kepler’s second law.

Kepler’s three laws of planetary motion are:(1) The law of ellipses: the planets move in el-liptical orbits with the Sun as a common fo-cus; (2) The law of areas: as a planet orbits theSun, the radial line joining the planet to the Sunsweeps out equal areas within the ellipse in equaltimes; and (3) The harmonic law: the square ofthe orbital period (P) of a planet is proportionalto the cube of its mean distance (a) from theSun. The third law states that there is a fixedratio between the time it takes a planet to com-plete an orbit around the Sun and the size of theorbit. Astronomers often express this ratio asP2/a3, where “a” is the semimajor axis of theellipse and “P” is the period of revolution aroundthe Sun. Kepler’s three laws established modernobservational astronomy on a solid mathematicalfoundation.

In 1627 Kepler’s Tabulae Rudolphinae (Rudol-phine tables), named after his benefactorEmperor Rudolf and dedicated to Brahe, pro-vided astronomers detailed planetary positiondata. The tables remained in use until the 18thcentury. Kepler used the logarithm to help per-form the tedious calculations, which was the first

important scientific application of the loga-rithm, a new mathematical function inventedby the Scottish mathematician, John Napier(1550–1617).

Kepler also made important contributions inthe field of optics. While in Prague, he wroteOptica (Optics) in 1604. Prior to 1610, Galileoand Kepler communicated with each other, al-though they never met. According to one his-toric account of their relationship, in 1610Kepler refused to believe that Jupiter had fourmoons that behaved like a miniature solar sys-tem, unless he personally observed them. Whena Galilean telescope arrived at his doorstep.Kepler promptly used the device and immedi-ately called the four major moons discovered byGalileo “satellites”—a term Kepler derived fromthe Latin word satelles meaning “the people whoescort or loiter around a powerful person.” In1611 Kepler improved the design of Galileo’soriginal telescope by introducing two convexlenses in place of the one convex lens and oneconcave lens arrangement used by the greatItalian astronomer. Kepler’s final published workin Prague was his Dioptrice (Dioptics), which hecompleted in 1611. This book is the first scien-tific work in geometrical optics.

Before his death in 1630, Kepler wrote anovel called Somnium (The dream), about anIcelandic astronomer who travels to the Moon,involving demons and witches who help get thehero to the Moon’s surface in a dream state.Kepler’s description of the lunar surface wasquite accurate. Therefore, many historians treatthis story, published after his death in 1634, asthe first genuine piece of science fiction.

Kepler married twice, fathered 13 children,constantly battled financial difficulties, and en-dured the turmoil of numerous relocations causedby religious persecution. He died on November15, 1630, in Regensburg, Bavaria, of a fever con-tracted while journeying to see the emperor.Kepler was trying to collect the payment owedhim for his service as imperial mathematician

186 al-Khwarizmi, Abu

and for his effort in producing the RudolphineTables. Newton regarded both Galileo andKepler as those “giants” upon whose shouldershe (Newton) stood to see farther into the mysteries and workings of the mechanical universe.

5 al-Khwarizmi, Abu (Abu’Jafar Muhammad ibn-Musa al-Khwarizmi)(ca. 780–850)ArabianMathematician, Astrologer, Astronomer,Geographer

The foundation for practical mathematics as itis known and used today is derived from the workof Abu al-Khwarizmi, who is most renowned as“the father of algebra.” But as a scholar of histime, broadly estimated between the years of770 to 850, al-Khwarizmi was a student, prac-titioner, and teacher of many scientific disci-plines—mathematics, astrology, astronomy, andgeography—because during this time the studyof the stars usually involved an understanding ofall of these sciences.

Science first made its appearance in a sig-nificant way in Baghdad under the rule of caliphs.During this time, many aspects of life wereconducted according to astronomy. Physicianspracticed medicine based on the stars, seekingstellar guidance for the best time to performmedical treatments. Agriculture was tied to as-tronomy, as is often the case today when al-manacs are consulted for the best time to plantand harvest. Calendars needed to be devised,and the passing of time using a moon-calendarcould only be told by looking at the night sky.Religious rituals, which required praying atprecise times and facing an exact direction (ge-ography), depended on the expert interpreta-tion of the heavens. And the lives and futuredestinies of rulers were decided amongst thestars.

In 813 the caliph Al-Ma’mun, who ruledfrom 813 to 833, ordered the translation of thework of a man from India who reportedly couldpredict eclipses, and al-Khwarizmi became thefirst person to publish astronomical tables basedon the Indian’s work. The Indian books, how-ever, were strictly numerical, with limited writtenexplanations. But because India had a numericalsystem that included the concept of zero, al-Khwarizmi was able to translate the tables andmove into a realm of mathematics that he devisedfor the average person to use in everyday life.

Al-Ma’mun’s reign was one that both sup-ported and promoted scientific study, and his ex-cellent skills during a peace negotiation with theByzantines made it possible for him to acquirePTOLEMY’s original work. Arab scientists againwent to work, this time translating Ptolemy, andthe result was the Almagest, created in about827. Ptolemy’s influence, and indeed some of hisexact measurements, can be found in the latter-day translations of al-Khwarizmi’s writings.

During this time, translating involved morethan changing the information from one lan-guage to another. Recalculation of measurementswas equally important, to assure an accurate read-ing. In essence, al-Khwarizmi was both compil-ing information and creating new astronomicaltables for his time and region.

Applying geography to the understanding ofastronomy, then, was a natural extension of de-veloping the tables. This led to the creation ofthe first map of the known world, completed in830, under the leadership of al-Khwarizmi withthe help of 70 other geographers. Determiningthe volume and circumference of the newlymapped Earth—a scientific blending of geogra-phy and astronomy—was another task under-taken by al-Khwarizmi for his caliph.

A gifted scientist, al-Khwarizmi workedwithin many disciplines as they related to as-tronomy and produced significant writings, thefundamentals of which have withstood cen-turies. Aside from his most noteworthy work in

Kirchhoff, Gustav Robert 187

algebra, Al-Jabrwa-al-Muqabilah, al-Khwarizmi’sscientific writings include his work on geogra-phy, Kitab Surat-al-Ard, which is based onPtolemy’s Geography and provides 2,402 distinctlongitude and latitude calculations that are gen-erally agreed to be more accurate than Ptolemy’scalculations; his writing on the Jewish calendar,Istikhraj Tarikh al-Yuhad; his work on sundials,Kitab al-Tarikh and Kitab al-Rukhmat; two workson the astrolabe, an instrument that was used inearly times to measure the angle between thehorizon and a celestial body; a horoscope ofprominent members of society that was writ-ten as a political history; and his title on as-tronomy, Sindhind zij, which covers astrologi-cal tables, calendars, and calculations relatingto the Sun, the Moon, and planets, as well aseclipses. Of this work, nearly all of the origi-nals are lost.

Abu al-Khwarizmi began his life’s worktranslating science. It is ironic, then, that all ofour knowledge of his scientific discovery comesfrom translations of his work by other men.

5 Kirchhoff, Gustav Robert(1824–1887)GermanPhysicist, Spectroscopist

This gifted German physicist collaborated withROBERT WILHELM BUNSEN in developing thefundamental principles of spectroscopy. Whileinvestigating the phenomenon of blackbody ra-diation, Kirchhoff applied spectroscopy to studythe chemical composition of the Sun—espe-cially the production of the Fraunhofer lines inthe solar spectrum. His pioneering work con-tributed to the development of astronomicalspectroscopy—one of the major tools in modernastronomy.

Gustav Robert Kirchhoff was born onMarch 12, 1824, in Königsberg, Prussia (nowKaliningrad, Russia). He was a student of Carl

Friedrich Gauss (1777–1855) at the Universityof Königsberg and graduated in 1847. While stilla student, he extended the work of Georg SimonOhm (1787–1854) by introducing his own setof physical laws (now called Kirchhoff ’s laws)to describe the network relationship betweencurrent, voltage, and resistance in electrical cir-cuits. Following graduation, Kirchhoff taught

Gustav Kirchhoff was the talented German physicistwho collaborated with Robert Bunsen in demonstratingthe principles of spectroscopy. A major breakthroughtook place when Kirchhoff applied spectroscopy tostudy the chemical composition of the Sun—especiallythe production of the Fraunhofer lines in the solarspectrum. His pioneering work contributed to thedevelopment of astronomical spectroscopy—one of themajor tools in modern astronomy. (AIP Emilio SegrèVisual Archives, W.F. Meggers Gallery of NobelLaureates)

188 Kirchhoff, Gustav Robert

as an unsalaried lecturer (Privatdozent) at theUniversity of Berlin and remained there for ap-proximately three years before joining theUniversity of Breslau as a physics professor. Fouryears later, he accepted a more prestigious ap-pointment as a professor of physics at theUniversity of Heidelberg and remained withthat institution until 1875. At Heidelberg hecollaborated with the German chemist Bunsenin a series of innovative experiments that sig-nificantly changed observational astronomythrough the introduction of astronomical spec-troscopy.

Prior to his innovative work in spectroscopy,Kirchhoff produced a theoretical calculationin 1857 at the University of Heidelberg demon-strating the physical principle that an alter-nating electric current flowing through azero-resistance conductor would flow throughthe circuit at the speed of light. His work be-came a key step for the Scottish physicist JamesClerk Maxwell (1831–79) during his formula-tion of electromagnetic wave theory.

Kirchhoff’s most significant contributions toastrophysics and astronomy were in the field ofspectroscopy. Fraunhofer’s work had establishedthe technical foundations of the science of spec-troscopy, but undiscovered was the fact that eachchemical element had its own characteristicspectrum. That critical leap of knowledge wasnecessary before physicists and astronomerscould solve the puzzling mystery of the Fraun-hofer lines and make spectroscopy an indispen-sable tool in both observational astronomy andnumerous other applications. In 1859 Kirchhoffachieved that giant step in knowledge, whileworking in collaboration with Bunsen at theUniversity of Heidelberg. In his breakthroughexperiment, Kirchhoff sent sunlight through asodium flame and, with the primitive spectro-scope he and Bunsen had constructed, observedtwo dark lines on a bright background just wherethe Fraunhofer D-lines in the solar spectrum oc-curred. He and Bunsen immediately concluded

that the gases in the sodium flame were absorb-ing the D-line radiation from the Sun, produc-ing an absorption spectrum.

After additional experiments, Kirchhoff alsorealized that all the other Fraunhofer lines wereactually absorption lines—that is, gases in theSun’s outer atmosphere were absorbing some ofthe visible radiation coming from the solar in-terior thereby creating these dark lines, or “holes”in the solar spectrum. By comparing solar spec-tral lines with the spectra of known elements,Kirchhoff and Bunsen detected a number of el-ements present in the Sun, with hydrogen beingthe most abundant. This classic set of experi-ments, performed in Bunsen’s laboratory inHeidelberg with a primitive spectroscope as-sembled from salvaged telescope parts, gaverise to the entire field of spectroscopy, includingastronomical spectroscopy.

Bunsen and Kirchhoff then applied theirspectroscope to resolving elemental mysteries onEarth. In 1861 they discovered the fourth andfifth alkali metals, which they named cesium(from the Latin caesium, meaning sky blue) andrubidium (from the Latin rubidus, meaning dark-est red). Today scientists use spectroscopy toidentify individual chemical elements from thelight each emits or absorbs when heated toincandescence.

Modern spectral analyses trace their her-itage directly back to the pioneering work ofBunsen and Kirchhoff. Astronomers and astro-physicists use spectra from celestial objects in anumber of important applications, includingcomposition evaluation, stellar classification,and radial velocity determination.

In 1875 Kirchhoff left Heidelberg becausethe cumulative effect of a crippling injury hesustained in an earlier accident now preventedhim from performing experimental research.Confined to a wheelchair or crutches, he ac-cepted an appointment to the chair of mathe-matical physics at the University of Berlin. Inthe new less physically demanding position, he

Korolev, Sergei Pavlovich 189

pursued numerous topics in theoretical physicsfor the remainder of his life. During this periodhe made significant contributions to the field ofradiation heat transfer. He discovered that theemissive power of a body to the emissive powerof a blackbody at the same temperature is equalto the absorptivity of the body. His work inblackbody radiation was fundamental in the de-velopment of quantum theory by MAX KARL

PLANCK.Recognizing his great contributions to

physics and astronomy, the British Royal Societyelected Kirchhoff as a fellow in 1875. Failinghealth forced him to retire prematurely in 1886from his academic position at the University ofBerlin. He died in Berlin on October 17, 1887,and some of his scientific work appeared posthu-mously. While at the University of Berlin, heprepared his most comprehensive publication,Lectures on Mathematical Physics (Vorlesungenüber mathematische Physik)—a four-volume ef-fort that appeared between 1876 and 1894. Hiscollaborative experiments with Bunsen and hisinsightful interpretation of their results started anew era in astronomy.

5 Korolev, Sergei Pavlovich(1907–1966)Ukrainian/RussianRocket Engineer

Sergei Korolev is often called the RussianWERNHER VON BRAUN, because he was the driv-ing technical force behind the initial intercon-tinental ballistic missile (ICBM) and the spaceexploration programs of the Soviet Union. In1954 he started work on the first Soviet ICBM,called the R-7. It was a powerful rocket designedto carry a massive nuclear warhead across con-tinental distances. As part of cold war politics,Soviet premier Nikita Khrushchev (1894–1971)gave Korolev permission to use that militaryrocket to place the world’s first artificial satel-

lite, Sputnik 1, into orbit around Earth. OnOctober 4, 1957, Korolev became the rocket en-gineer who started the Space Age.

Korolev was born on January 12, 1907, inZhitomir, the Ukraine—at the time part ofczarist Russia. Korolev’s birth date sometimesappears as December 30, 1906, a date corre-sponding to an obsolete czarist calendar sys-tem. As a young boy, Korolev obtained hisfirst ideas about space travel in the inspira-tional books of KONSTANTIN EDUARDOVICH

TSIOLKOVSKY. After discovering the rocket,Korolev decided on a career in engineering.He entered Kiev Polytechnic Institute in 1924and two years later transferred to Moscow’sBauman High Technical School, where hestudied aeronautical engineering under such fa-mous Russian aircraft designers as AndreyTupolev. Korolev graduated as an aeronauticalengineer in 1929.

He began to champion rocket propulsion in1931, when he helped to organize the MoscowGroup for the Investigation of Reactive Motion,(Gruppa Isutcheniya Reaktvnovo Dvisheniya)(GIRD). Like its German counterpart, theVerein für Raumschiffahrt (VFR), (the GermanSociety for Space Travel), this Soviet technicalsociety began testing liquid-propellant rockets ofincreasing size. In 1933 GIRD merged with asimilar group from Leningrad (St. Petersburg)to form the Reaction Propulsion ScientificResearch Institute (RNII). Korolev was veryactive in this new organization and encouragedits members to develop and launch a series ofrocket-propelled missiles and gliders duringthe mid-1930s. The crowning achievement ofKorolev’s early aeronautical engineering effortswas his creation of the RP-318, Russia’s firstrocket-propelled aircraft.

In 1934 the Soviet Ministry of Defensepublished Korolev’s book Rocket Flight into theStratosphere. Between 1936 and 1938, he super-vised a series of rocket engine tests and winged-rocket flights within RNII. However, Soviet

190 Korolev, Sergei Pavlovich

dictator Joseph Stalin (1879–1953) was elimi-nating many intellectuals through a series ofbrutal purges. Despite his technical brilliance,Korolev, along with most of the staff at RNII,found themselves imprisoned in 1938. DuringWorld War II Korolev remained in a scientificlabor camp. His particular prison design bureau,called Sharashka TsKB-29, worked on jet-as-sisted take-off (JATO) systems for aircraft.

Freed from the labor camp after the war,Korolev resumed his work on rockets. He ac-cepted an initial appointment as the chief con-structor for the development of a long-rangeballistic missile. At this point in his life, Korolevessentially disappeared from public view, and allhis rocket and space activities remained a tightlyguarded state secret.

Following World War II Stalin becamemore preoccupied with developing an atomicbomb than with exploiting captured German V-2rocket technology. But he apparently sanctionedsome work on long-range rockets and also ap-proved the construction of a ballistic missile testrange at Kapustin Yar, near the city of Volgograd.It was this approval that allowed Korolev to forma group of rocket experts to examine capturedGerman rocket hardware and to resume theSoviet rocket research program. In late October1947 Korolev’s group successfully test-fired acaptured German V-2 rocket from the newlaunch site at Kapustin Yar. By 1949 Korolev haddeveloped a new rocket, the Pobeda (Victory-class) ballistic missile. He used Russian-modifiedGermanV-2 rockets and Pobeda rockets to sendinstruments and animals into the upper atmos-phere. In May 1949 one of his modified V-2rockets lifted a 120-kilogram payload to an alti-tude of 110 kilometers.

As cold war tensions mounted between theSoviet Union and the United States in 1954,Korolev began work on the first Soviet ICBM.Soviet leaders were focusing their nation’s de-fense resources on developing very powerfulrockets to carry the country’s much heavier, less

design-efficient nuclear weapons. Respondingto this emphasis, Korolev designed the R-7.This powerful rocket was capable of carrying a5,000-kilogram payload more than 5,000 kilo-meters.

With the death of Stalin in 1953, a newleader, Nikita Khrushchev, decided to useSoviet technology accomplishments to empha-size the superiority of Soviet communism overWestern capitalism. Under Khrushchev, Korolevreceived permission to send some of his pow-erful military missiles into the heavens onmissions of space exploration, as long as suchspace missions also had high-profile politicalbenefits.

In summer 1955 construction began on asecret launch complex in a remote area ofKazakhstan north of a town called Tyuratam.This central Asian site is now called theBaikonur Cosmodrome and lies within the po-litical boundaries of the Republic of Kazakhstan.In August and September 1957 Korolev success-fully launched the R-7, on long-range demon-stration flights from this location. Encouragedby the success of these test flights, Khrushchevallowed Korolev to use an R-7 military missileas a space launch vehicle in order to beat theUnited States into outer space with the firstartificial satellite.

On October 4, 1957, a mighty R-7 rocketroared from its secret launch pad at Tyuratam,placing Sputnik 1 into orbit around Earth. Korolev,the “anonymous” engineering genius, had pro-pelled the Soviet Union into the world spotlightand started the Space Age. To Khrushchev’s de-light, a supposedly technically inferior nationwon a major psychological victory against theUnited States. With the success of Sputnik 1,space technology became a key instrument ofcold war politics and superpower competition.

The provocative and boisterous Khrushchevimmediately demanded additional high-visibilityspace successes from Korolev. The rocket engineerresponded on November 3, 1957, by placing a

Korolev, Sergei Pavlovich 191

much larger satellite into orbit. Sputnik 2 car-ried the first living space traveler into orbitaround Earth. The passenger was a dog namedLaika. Korolev continued to press the SovietUnion’s more powerful booster advantage bydeveloping the Vostok (one-person) spacecraftto support human space flight. On April 12,1961, another of Korolev’s powerful militaryrockets placed the Vostok 1 spacecraft, carry-ing cosmonaut Yuri Gagarin (1934–68), intoorbit around Earth. Gagarin’s brief flight (onlyone orbital revolution) took place just beforethe United States sent its first astronaut, AlanB. Shepard Jr. (1923–99), on a suborbital mis-sion from Cape Canaveral, Florida, on May 5,1961.

Using Korolev’s powerful rockets like somany trump cards, Khrushchev continued toreap international prestige for the Soviet Union,which had just become the first nation to placea person into orbit around Earth. This particu-lar Soviet accomplishment forced U.S. presidentJohn F. Kennedy (1917–63) into a daring re-sponse. In May 1961 Kennedy announced hisbold plan to land U.S. astronauts on the Moonin less than a decade. From the perspective ofhistory, Korolev’s space achievements becamethe political catalyst by which Braun received amandate to build more powerful rockets for theUnited States. Starting in July 1969, Braun’s newrockets would carry U.S. explorers to the surfaceof the Moon—a technical accomplishment thatsoundly defeated the Soviet Union in the greatspace race of the 1960s.

Following the success of Sputnik, Korolevused his rockets to propel large Soviet spacecraftto the Moon, Mars, and Venus. One of his space-craft, Lunik 3, took the first photographic im-ages of the Moon’s far side in October 1959.These initial images of the Moon’s long-hiddenhemisphere excited both astronomers and thegeneral public. Appropriately, one of the largestfeatures on the Moon’s far side now bearsKorolev’s name. He also planned a series of

interesting follow-on Soyuz spacecraft for futurespace projects involving multiple human crews.However, he was not allowed to pursue thesedevelopments in a logical, safe fashion.

Premier Khrushchev kept demanding otherspace mission “firsts” from Korolev’s team. TheSoviet leader wanted to fly a three-person crewin space before the United States could com-plete the first flight of its new two-person Geminicapsule. The first crewed Gemini flight occurredon March 23, 1965. Korolev recognized howdangerous it would be to convert his one-personVostok spacecraft design into an internallystripped-down “three-seater.” But he also re-membered the painful time he spent in a polit-ical prison camp for perceived disloyalty toStalin’s regime.

So, despite strong opposition from his de-sign engineers, Korolev removed the Vostokspacecraft’s single ejection seat and replaced itwith three couches. Without an ejection seat,the cosmonaut crew could not leave the spacecapsule during the final stages of reentry descent,as had been done during previous successfulVostok missions. To accommodate the demandsof this mission, Korolev came up with severalclever ideas, including a new retro-rocket systemand a larger reentry parachute. To quell the ve-hement safety objections from his design team,he also made them an offer they could not refuse:If they could design this modified three-personspacecraft in time to beat the Americans, one ofthe engineers would be allowed to participate inthe flight as a cosmonaut.

On October 12, 1964, a powerful militarybooster sent the “improvised” Voskhod 1 spacecapsule into a 170 kilometer by 409 kilometerorbit around Earth. Voshkod is the Russian wordfor “sunrise.” The flight lasted just one day. Theretrofitted Vostok spacecraft carried three cosmo-nauts without spacesuits under extremely crampedconditions. Cosmonaut Vladimir Komarov com-manded the flight; a medical expert, Boris Yegorov,and a design engineer, Konstantin Feoktistov,

192 Kuiper, Gerard Peter

accompanied him. Korolev won an extremelyhigh-risk technical gamble. His engineering skilland luck not only satisfied Khrushchev’s insa-tiable appetite for politically oriented space ac-complishments, but he also kept his promise ofa ride in space to one of his engineers.

Khrushchev responded to Kennedy’s moonrace challenge by ordering Korolev’s ExperimentalDesign Bureau No. 1 (OKB-1) to accelerate itsplans for a very large booster. As originally en-visioned by Korolev, the Russian N-1 rocket wasto be a very large and powerful booster for plac-ing extremely heavy payloads into Earth’s orbit,including space stations, nuclear-rocket upperstages, and various military payloads. But afterKorolev’s untimely death in 1966, the highlysecret N-1 rocket became the responsibility ofanother rocket design group. It suffered fourcatastrophic failures between 1969 and 1972,and then the project was quietly canceled.

From 1962 to 1964, Khrushchev’s continuedpolitical use of space technology seriously di-verted Korolev’s creative energies from muchmore important projects, such as new boosters,the Soyuz spacecraft, a Moon-landing mission,and the space station. His design team was justbeginning to recover from Khrushchev’s con-stant interruptions when disaster struck. OnJanuary 14, 1966, Korolev died during a botchedroutine surgery at a hospital in Moscow. He wasonly 58 years old. Some of Korolev’s contribu-tions to space technology include the powerful,legendary R-7 rocket (1956), the first artificialsatellite (1957), pioneering lunar spacecraft mis-sions (1959), the first human space flight (1961),a spacecraft to Mars (1962), and the first spacewalk (1965). Even after his death, the Sovietgovernment chose to hide Korolev’s identity bypublicly referring to him only as the “ChiefDesigner of Carrier Rockets and Spacecraft.”Despite this official anonymity, Chief Designerand Academician Korolev is now properly rec-ognized as the rocket engineer who started theSpace Age.

The Dutch-American planetary astronomer GerardKuiper was the exceptionally skilled observer who in1944 discovered that Saturn’s largest moon, Titan, hadan atmosphere. In the late 1940s he helped reviveinterest in planetary astronomy, when he foundMiranda, the fifth largest moon of Uranus in 1948,and Nereid, the outermost moon of Neptune, in1949. He also postulated the existence of a largereservoir of small icy bodies beyond the orbit ofPluto—now called the Kuiper belt in his honor.(AIP Emilio Segrè Visual Archives, Physics TodayCollection)

5 Kuiper, Gerard Peter (Gerrit Pieter)(1905–1973)Dutch/AmericanAstronomer

In 1951 Gerard Kuiper, the Dutch-Americanplanetary astronomer, boldly postulated thepresence of thousands of icy planetesimals in anextended region at the edge of the solar systembeyond the orbit of Pluto. Today, this region offrigid, icy objects has been detected and is calledthe Kuiper belt in his honor. In 1944 Kuiper dis-covered that Saturn’s largest moon, Titan, hadan atmosphere. He continued to revive interestin planetary astronomy by discovering Miranda,the fifth-largest moon of Uranus, in 1948, andNereid, the outermost moon of Neptune, in

Kuiper, Gerard Peter 193

1949. Transitioning to Space Age astronomy,he served with distinction as a scientific adviserto the U.S. National Aeronautics and SpaceAdministration (NASA) on the early lunarand planetary missions in the 1960s, especiallyNASA’s Ranger Project and Surveyor Project.

Gerard Kuiper was born on December 7,1905, in Harenkarspel, the Netherlands. Whenhe was young, two factors influenced Kuiper’sinterest in astronomy. First, his father gave hima gift of a small telescope that he used to greatadvantage because of his exceptional visualacuity. Second, he was drawn to astronomy bythe cosmological and philosophical writings ofthe great French mathematician René Descartes(1596–1650).

While enrolling at the University of Leidenin September 1924, Kuiper made the acquain-tance of a fellow student, BARTHOLOMEUS JAN

BOK, who would remain a lifelong friend. He com-pleted a bachelor of science degree in 1927 andimmediately pursued his graduate studies. One ofKuiper’s professors at the University of Leiden wasEJNAR HERTZSPRUNG, under whom he did his doc-toral thesis on the subject of binary stars. Afterreceiving his doctoral degree in 1933, Kuiper trav-eled to the United States under a fellowship andconducted postdoctoral research on binary starsat the Lick Observatory, near San Jose, California.

In August 1935 he left California and spenta year at the Harvard College Observatory.While there, he met and later married (in June1936) Sarah Parker Fuller, whose family had do-nated the property on which the Harvard OakRidge Observatory stood. The couple had twochildren: a son and a daughter. In 1936 Kuiperjoined the Yerkes Observatory of the Universityof Chicago. He became a naturalized Americancitizen the following year. He joined other mem-bers of the Yerkes staff who worked with theUniversity of Texas in planning and developingthe McDonald Observatory, near Fort Davis,Texas. The 2.1-meter reflector of this importantastronomical facility was dedicated and began

operation in 1939. At the University of Chicago,Kuiper progressed up through the academic ranks,becoming a full professor of astronomy in 1943.

In an important 1941 technical paper,Kuiper introduced the concept of “contact bi-naries”—a term describing close, mass-exchangebinary stars characterized by accretion disks.During World War II, he took a leave of absencefrom the University of Chicago to support vari-ous defense-related projects. His duties includedspecial technical service missions as a memberof the U.S. War Department’s ALSOS Mission,which assessed the state of science in NaziGermany during the closing days of the war. Inone of his most interesting adventures, he helpedrescue MAX KARL PLANCK from the advancingSoviet armies. Kuiper, an astronomer turnedcommando, took charge of a military vehicle anddriver, dashed across war-torn Germany from theU.S. lines to Planck’s location in eastern Ger-many, and then spirited the aging German physi-cist and his wife away to a safe location in thewestern part of Germany near Göttingen.

While performing his wartime service, Kuiperstill managed to make a major contribution tomodern planetary astronomy, the astronomicalarea within which he would become the recog-nized world leader. Taking a short break from hiswartime research activities in winter 1943–44,Kuiper conducted an opportunistic spectro-scopic study of the giant planets Jupiter andSaturn and their major moons at the McDonaldObservatory. To his great surprise, early in 1944he observed methane on the largest Saturnianmoon, Titan—making the large moon the onlysatellite in the solar system with an atmosphere.This fortuitous discovery steered Kuiper into hisvery productive work in solar system astronomy,especially the study of planetary atmospheres.

Through spectroscopy he discovered in 1948that the Martian atmosphere contained carbondioxide. In 1948 he discovered the fifth moon ofUranus, which he named Miranda, and thenNeptune’s second moon, Nereid, in 1949. He

194 Kuiper, Gerard Peter

(1961); the Rectified Lunar Atlas (1963); and theConsolidated Lunar Atlas (1967).

Kuiper was also a pioneer in applying in-frared technology to astronomy and played a veryinfluential role in the development of airborneinfrared astronomy in the 1960s and early 1970s.Starting in 1967 Kuiper used NASA’s Convair990 jet aircraft, which was equipped with a tel-escope system capable of performing infraredspectroscopy. As the aircraft flew above 40,000feet, Kuiper and his research assistants performedtrend-setting infrared spectroscopy measure-ments of the Sun and other stars, as well as plan-ets, discovering many interesting phenomenathat could not be observed by ground-based as-tronomers because of the blocking influence ofthe denser portions of Earth’s atmosphere.

Kuiper died on December 24, 1973, whileon a trip to Mexico City with his wife and sev-eral family friends. As one tribute to his numer-ous contributions to astronomy, in 1975 NASAnamed its newest airborne infrared observatory,a specially outfitted C-141 jet transport air-craft, the Gerard P. Kuiper Observatory (KAO).This unique airborne astronomical facility oper-ated out of Moffett Field, California, for morethan two decades until it was retired from servicein October 1995.

Kuiper received the Janssen Medal in 1947from the Astronomical Society of France and theKepler Medal in 1971 from the AmericanAssociation for the Advancement of Scienceand the Franklin Institute. He was also electedas a member of the American Academy ofSciences in 1950. No astronomer did more inthe 20th century to revitalize planetary astron-omy. Celestial objects carry his name or continuehis legacy of discovery across the entire solar sys-tem, from a specially named crater on Mercury,to Miranda around Uranus, to Nereid aroundNeptune, to an entire cluster of icy minor plan-ets beyond Pluto.

went on to postulate the existence of a regionof icy planetesimals and minor planets beyondthe orbit of Pluto. The first members of this re-gion, now called the Kuiper belt in his honor,would be detected in the early 1990s.

Kuiper left the University of Chicago andjoined the University of Arizona in 1960. AtArizona, he founded and directed the Lunarand Planetary Laboratory, making major con-tributions to planetary astronomy at the dawnof the Space Age. He produced major lunar at-lases for both the U.S. Air Force and NASA.His research concerning the Moon in the1950s and 1960s provided strong support forthe impact theory of crater formation. Prior tothe Space Age, most astronomers held that thecraters on the Moon had been formed by vol-canic activity.

Kuiper promoted a multidisciplinary ap-proach to the study of the solar system, and thisemphasis stimulated the creation of a new as-tronomical discipline called planetary science.He assisted in the selection of the superiorground-based observatory site at Mauna Kea, onthe island of Hawaii. Because of his reputationas an outstanding planetary astronomer, heserved as a scientific adviser on many of NASA’s1960 and 1970 space missions to the Moon andthe inner planets. Kuiper was the chief scientistfor NASA’s Ranger Project (1961–65), whichsent robot spacecraft equipped with televisioncameras crashing into the lunar surface. Later,he helped identify suitable landing sites forNASA’s Surveyor robot-lander spacecraft as wellas the Apollo human-landing missions.

He served as principal author or general ed-itor on several major works in modern astron-omy, including The Solar System, a four-volumeseries published between 1953 and 1963; Starsand Stellar Systems, a nine-volume series appear-ing in 1960; the famous Photographic Atlas of theMoon (1959); the Orthographic Atlas of the Moon

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L5 Lagrange, Comte Joseph-Louis

(Lodovico Lagrange, Luigi Lagrange,Giuseppe Luigi Lagrangia)(1736–1813)Italian/FrenchMathematician, Celestial MechanicsExpert

The 18th-century mathematician Joseph Lagrangemade significant contributions to celestial me-chanics. In about 1772 he identified certainspecial regions in outer space—now called theLagrangian libration points—that mark the fiveequilibrium points for a small celestial objectmoving under the gravitational influence of twomuch larger bodies. Other astronomers used hisdiscovery of the Lagrangian libration points tofind new objects in the solar system, such as theTrojan Group of asteroids. His influential book,Analytical Mechanics, represented an elegantcompendium of the mathematical principlesthat described the motion of heavenly bodies.

Lagrange was born on January 25, 1736, inTurin, Italy. His father, Giuseppe FrancescoLodovico Lagrangia, was a prosperous public of-ficial in the service of the king of Savoy, but im-poverished his family through unwise financialinvestments and speculations. Lagrange, a gen-tle individual with a brilliant mathematicalmind, recalled his childhood poverty by later

quipping: “If I had been rich, I probably wouldnot have devoted myself to mathematics.”Although given an Italian family name at bap-tism, throughout his life Lagrange preferred toemphasize his French ancestry, derived from hisfather’s side of the family. He would, therefore,sign his name “Luigi Lagrange” or “LodovicoLagrange”—combining an Italian first namewith a French family name.

Lagrange studied at the College of Turin,enjoying instruction in classical Latin andignoring Greek geometry. But after reading SIR

EDMUND HALLEY’s treatise on the application ofalgebra in optics, Lagrange changed his earliercareer plans to become a lawyer and embracedthe study of higher mathematics. In 1755 he wasappointed professor of mathematics at the RoyalArtillery School in Turin. At the time, Lagrangewas just 19 years old and already exchanging im-pressive mathematical notes on his calculus ofvariations with the famous Swiss mathematicianLEONHARD EULER. In 1757 Lagrange became afounding member of a local scientific group thateventually evolved into the Royal Academy ofScience of Turin. He published many of his el-egant papers on the calculus of variations in thesociety’s journal, Mélanges de Turin.

By the early 1760s Lagrange had earned areputation as one of Europe’s most gifted math-ematicians. Yet he was a humble person who did

196 Lagrange, Comte Joseph-Louis

not seek fame or position. He just wanted to pur-sue the study of mathematics with a modestamount of financial security. In 1764 Lagrangereceived a prize from the Paris Academy ofSciences for his brilliant mathematical paper onthe libration of the Moon. The Moon’s librationis the phenomenon by which 59 percent of the

lunar surface is visible to an observer on Earthover a period of 30 years. This results from acomplicated collection of minor perturbationsin the Moon’s orbit as it travels around Earth.Soon after that award, he won another prizefrom the Paris Academy in 1776 for his theoryon the motion of Jupiter’s moons.

When Euler left Berlin in 1766 to return toSt. Petersburg, he recommended to King FrederickII of Prussia that Lagrange serve as his replace-ment. Therefore, in November 1766 FrederickII invited Lagrange to succeed Euler as math-ematical director of the Berlin Academy ofScience of the Prussian Academy of Sciences. Alittle less than a year after his arrival in Berlin,Lagrange married Vittoria Conti, a cousin whohad lived for an extended time with his familyin Turin. The couple had no children.

For two decades Lagrange worked in Berlinand during this period produced a steady num-ber of top quality, award-winning mathematicalpapers. He corresponded frequently with PIERRE-SIMON MARQUIS DE LAPLACE, a contemporaryFrench mathematician living in Paris. Lagrangewon prizes from the Paris Academy of Sciencesfor his mathematics in 1772, 1774, and 1780. Heshared the 1772 Paris Academy prize with Eulerfor his superb work on the challenging three-body problem in celestial mechanics—an effortthat involved the existence and location of theLagrangian libration points. These five points(usually designated as L1, L2, L3, L4, and L5) arethe locations in outer space where a small ob-ject can experience a stable orbit in spite of theforce of gravity exerted by two much more mas-sive celestial bodies when they all orbit abouta common center of mass. He won the 1774prize for another brilliant paper on the motionon the Moon. His 1780 award-winning effortdiscussed the perturbation of cometary orbits bythe planets.

However, during his 20 years in Berlin, hishealth began to fail. His wife also suffered frompoor health, and she died in 1783 after an

The gifted 18th-century Italian-French mathematicianJoseph Lagrange made important contributions tocelestial mechanics, extending the work begun by SirIsaac Newton. In about 1772 Lagrange identifiedseveral special regions in outer space—now called theLagrangian libration points—that correspond to thefive equilibrium points for a small celestial objectmoving under the gravitational influence of two muchlarger bodies. Later observational astronomers, such asMax Wolf, used knowledge of the Lagrangian librationpoints to find new objects in the solar system, such asthe Trojan Group of asteroids. (AIP Emilio Segrè VisualArchives, E. Scott Barr Collection)

Laplace, Pierre-Simon, Marquis de 197

extended illness. Her death plunged Lagrangeinto a state of depression. After the death ofFrederick II, Lagrange departed from Berlin toaccept an invitation from the French king LouisXVI. In May 1787 Lagrange became a memberof the Paris Academy of Sciences, a position heretained for the rest of his career despite the tur-moil of the French Revolution. Upon Lagrange’sarrival in Paris, King Louis XVI offered Lagrangeapartments in the Louvre, from which comfort-able surroundings he published in 1788 his ele-gant synthesis of mechanics, entitled Mécaniqueanalytique (Analytical mechanics), which he hadwritten in Berlin.

In May 1790 Lagrange became a member ofand eventually chaired the committee of theParis Academy of Sciences that standardizedmeasurements and created the internationalsystem (Système Internationale, or SI) of unitscurrently used throughout the world. In 1792Lagrange married his second wife, a muchyounger woman, named Renée Le Monnier, thedaughter of one of his astronomer colleagues atthe Paris Academy of Sciences.

Following the Reign of Terror (1793),Lagrange became the first professor of analysis atthe famous École Polytechnique, founded inMarch 1794. Though brilliant, the aging mathe-matician was not an accomplished lecturer, andmuch of what he discussed sailed over the headsof his audience of inattentive students. Despitehis shortcomings, the notes from his calculuslectures were collected and published as theTheory of Analytic Functions (1797) and Lessonson the Calculus of Functions (1804)—the firsttextbooks on the mathematics of real analyticalfunctions.

In 1791 the Royal Society in London madehim a Fellow. Napoleon, the emperor of France,bestowed many honors upon the aging mathe-matician, making him a senator, a member ofthe Legion of Honor, and a count of the empire.Despite the lavish political attention, Lagrangeremained a quiet academician who preferred to

keep himself absorbed in his thoughts aboutmathematics. He died in Paris on April 10, 1813.His numerous works on celestial mechanics pre-pared the way for 19th-century mathematicalastronomers to make discoveries using the sub-tle perturbations and irregularities in the motionof solar system bodies.

5 Laplace, Pierre-Simon, Marquis de(1749–1827)FrenchMathematician, Astronomer, CelestialMechanics Expert

Called the “French Newton,” Pierre-SimonLaplace’s work in celestial mechanics establishedthe foundations of 19th-century mathematicalastronomy. Laplace extended SIR ISAAC NEWTON’sgravitational theory and provided a more com-plete mechanical interpretation of the solarsystem, including the subtle perturbations ofplanetary motions. His mathematical formula-tions supported the discovery of Uranus (18thcentury), Neptune (19th century), and Pluto(20th century). In 1796, apparently independ-ent of IMMANUEL KANT, Laplace introducedhis own version of the nebula hypothesis—suggesting that the Sun and the planets hadcondensed from a primeval interstellar cloudof gas.

Laplace was born on March 23, 1749, atBeaumont-en-Auge, in Normandy, France. Theson of a moderately prosperous farmer, he at-tended a Benedictine priory school in Beaumont,a preparatory school for future members of theclergy or military. At age 16 Laplace enrolled inthe University of Caen, where he studied theol-ogy in response to his father’s wishes. However,after two years at the university, Laplace discov-ered his great mathematical abilities and aban-doned any plans for an ecclesiastical career.

At 18 he left the university without receiv-ing a degree and went to live in Paris. There

198 Laplace, Pierre-Simon, Marquis de

Laplace met Jean d’Alembert (1717–83) andgreatly impressed the French mathematician andphilosopher. D’Alembert secured an appoint-ment for Laplace at the prestigious ÉcoleMilitaire. By age 19 Laplace had become theprofessor of mathematics at the school.

In 1773 he began to make his important con-tributions to mathematical astronomy. Workingindependently of, but cooperatively (throughcorrespondence) with COMTE JOSEPH-LOUIS

LAGRANGE, who then resided in Berlin, Laplace

applied and refined Newton’s law of gravitationto bodies throughout the solar system. Carefulobservations of the six known planets and theMoon indicated subtle irregularities in theirorbital motions. This raised a very puzzlingquestion: How could the solar system remainstable? Newton, for all his great scientific con-tributions, considered this particular problem fartoo complicated to be treated with mathemat-ics. He simply concluded that “divine interven-tion” took place on occasion to keep the entiresystem in equilibrium.

Laplace, however, was determined to solvethis problem with his own excellent skills inmathematics. Eighteenth-century astronomerscould not explain why Saturn’s orbit seemed tobe continually expanding, while Jupiter’s orbitseemed to be getting smaller. Laplace was ableto mathematically demonstrate that while therecertainly were measured irregularities in theorbital motions of these giant planets, suchanomalies were not cumulative, but ratherperiodic and self-correcting. His important dis-covery represented a mathematically and physi-cally sound conclusion that the solar system wasactually an inherently stable system.

As a result of this brilliant work, Laplacebecame recognized as one of France’s greatmathematicians. In 1773 Laplace became an as-sociate member of the French Academy ofSciences; he became a full member in 1785.However, as his fame grew, he more frequentlyacted the part of a political opportunist ratherthan a great scientist, tending to forget his hum-ble roots and rarely acknowledging his manybenefactors and collaborators. Good fortunecame to Laplace in 1784, when he became anexaminer at the Royal Artillery Corps. He eval-uated young cadets who would soon serve in theFrench army. While fulfilling this duty in 1785,he had the opportunity to grade the perform-ance of and pass a 16-year-old cadet namedNapoleon Bonaparte. The examiner positionallowed Laplace to make direct contact with

Marquis Laplace is often called the “French Newton.”A brilliant mathematician, his work in celestialmechanics established the foundations of 19th-centurymathematical astronomy. Laplace extended Newton’sgravitational theory to provide a more completemechanical interpretation of the solar system. Hespecifically addressed those subtle perturbations inplanetary motions that appeared to threaten the long-term stability of the solar system. His mathematicalformulations proved that the solar system was stableand supported the discovery of Uranus (18th century),Neptune (19th century), and Pluto (20th century).(AIP Emilio Segrè Visual Archives)

Laplace, Pierre-Simon, Marquis de 199

many of the powerful men who would run Franceduring its next four politically turbulent decades,including the monarchy of Louis XVI, the rev-olution, the rise and fall of Napoleon, and therestoration of the monarchy under Louis XVIII.While other great scientists, such as Antoine–Laurent Lavoisier (1743–94), would quite liter-ally lose their heads around him, Lagrange main-tained an ability to correctly change his viewsto suit the changing political events.

In 1787 Lagrange left Berlin and joinedLaplace in Paris. Despite a rivalry between them,the great mathematical geniuses benefited fromtheir constant exchange of ideas. They bothserved on the commission of the French Academyof Sciences that developed the metric system, al-though Laplace was eventually discharged fromthe commission during the Reign of Terror.Laplace married Marie-Charlotte de Courty deRomanges in May 1788. His wife was 20 yearsyounger than Laplace and bore him two children.Just before the Reign of Terror began, Laplace de-parted Paris with his wife and two children, andthey did not return until after July 1794.

Laplace published Exposition du système dumonde (The system of the world) in 1796. Thisbook was a five-volume popular (that is, non-mathematical) treatment of astronomy and ce-lestial mechanics. From a historic perspective, italso served as the precursor for his more detailedmathematical work on the subject. Laplace usedthis book to introduce his version of the nebu-lar hypothesis, in which he suggested that theSun and planets formed from the cooling andgravitational contraction of a large, flattenedand slowly rotating gaseous nebula. Apparently,Laplace was unaware that Kant had proposed asimilar hypothesis about 40 years earlier. Laplacewrote this book in such exquisite prose thatin 1816 he won admission to the FrenchAcademy—an honor only rarely bestowed uponan astronomer or mathematician. In 1817 heserved as president of this distinguished and ex-clusive literary organization.

Between 1799 and 1825, Laplace summedup gravitational theory and completed Newton’spioneering work in a monumental five-volumework, entitled Mécanique Céleste (Celestialmechanics). Laplace provided a complete me-chanical interpretation of the solar system andhis application of the law of gravitation. Centralto this work is Laplace’s great discovery of theinvariability of the mean motions of the plan-ets. With this finding, he demonstrated the in-herent stability of the solar system and gainedrecognition throughout his country and the restof Europe as the “French Newton.”

Laplace maintained an extraordinarily highscientific output despite the tremendous politi-cal changes taking place around him. He alwaysdemonstrated political adroitness and changedsides whenever it was to his advantage. UnderNapoleon he became a member and then chan-cellor of the French senate, received the Legionof Honor in 1805, and became a count of theempire in 1806. Yet when Napoleon fell frompower, Laplace quickly supported restoration ofthe monarchy and was rewarded by King LouisXVIII, who named him a marquis in 1817.

Laplace made scientific contributions be-yond his great work in celestial mechanics. Heprovided the mathematical foundation for prob-ability theory in two important books. In 1812he published his Théorie analytique des probabili-tiés (Analytic theory of probability) in which hepresented many of the mathematical tools he in-vented to apply probability theory to games ofchance and events in nature, including astron-omy and collisions of comets and planets. Healso wrote a popular discussion of probabilitytheory, Essai philosophique sur les probabilitiés (Aphilosophical essay on probability) that appearedin 1814.

Laplace also explored other areas of physi-cal science and mathematics between 1805 and1820. These areas included heat transfer, capil-lary action, optics, the behavior of elastic fluids,and the velocity of sound. However, as other

200 Leavitt, Henrietta Swan

physical theories began to emerge with their in-telligent young champions, Laplace’s dominantposition in French science came to an end. Hedied in Paris on March 5, 1827. ThroughoutFrance and Europe, Laplace was highly regardedas one of the greatest scientists of all time. Heheld membership in many foreign societies, in-cluding the British Royal Society, which electedhim a Fellow in 1789.

5 Leavitt, Henrietta Swan(1868–1921)AmericanAstronomer

It is a startling coincidence that Henrietta SwanLeavitt, another one of the “computers” hired at

the beginning of the 20th century by professorEDWARD CHARLES PICKERING to make complexdata analyses at the Harvard Observatory, con-tributed to astronomy while suffering almosttotal deafness, the same condition as her famouscoworker, ANNIE JUMP CANNON.

Leavitt was born on July 4, 1868, in Cambridge,Massachusetts, the daughter of a Congregationalminister. She attended Oberlin College andthen Radcliffe College, which was then calledthe Society for Collegiate Instruction of Women.She graduated with a B.A. degree from Radcliffein 1892, having become interested in astronomyin her senior year, and, to pursue her new in-terest, enrolled in further courses in astronomy.

Leavitt suffered a serious illness, however,which left her nearly deaf, forcing her to spenda few years at home. Eventually she volunteered

In about 1912, while working at the Harvard College Observatory, the talented American astronomer HenriettaLeavitt discovered the period-luminosity relationship for Cepheid variable stars. Her important finding permittedother astronomers, such as Harlow Shapley, to make more accurate estimates of distances in the Milky WayGalaxy. (Photo courtesy Margaret Harwood, AIP Emilio Segrè Visual Archives, Shapley Collection)

Lemaître, Abbé Georges-Édouard 201

to work at the Harvard College Observatory asa research assistant, seeking to gather experienceas an astronomer. Seven years later, in 1902,Professor Pickering hired her at 30 cents an hourto be one of his computers. In this capacity shedrifted toward the photometric side of the as-tronomy department, and became specialized inphotographing stars as a method of determiningtheir magnitude.

In 1904, after spending almost all of her timesearching photographic plates for Cepheid vari-ables, variable stars whose brightness changes dueto alternate expansions and contractions in vol-ume, Leavitt discovered 152 variables in theLarge Magellanic Cloud (LMC) and 59 in theSmall Magellanic Cloud (SMC). The followingyear she reported 843 new variables in the SMC.

In 1912 Leavitt devised the “period-luminos-ity” relationship, the direct correlation betweenthe time it took a star to go from brightest todimmest, which allowed astronomers to deter-mine the exact brightness of a star. Todayastronomers use the period-luminosity relation-ship to determine the distance of galaxies fromthe Earth.

With this knowledge, she studied 299 platesfrom 13 different telescopes, using logarithmicequations to classify stars over 17 degrees of mag-nitude and developing a standard of photographicmeasurements, eventually known as the HarvardStandard. In 1913 the International Committeeon Photographic Magnitudes accepted the stan-dard that Leavitt described. In the course of herstudies, Leavitt also discovered four novae andmore than 2,400 variables, approximately half ofthe total known to exist at the time.

Leavitt was a member of Phi Beta Kappa,the American Association of University Women,the American Astronomical and AstrophysicalSociety, the American Society for the Advance-ment of Science, and an honorary member of theAmerican Association of Variable Star Observers.

Without Leavitt’s pioneering work, modernastronomers would not be able to calculate the

distance from the Earth to faraway galaxies. Shewas working on a new photographic magnitudescale when she died of cancer in 1921. Four yearslater, the Swedish Academy of Sciences recog-nized her contribution to science by nominatingher for the Nobel Prize. A crater on the moonwas named Leavitt to honor the work of deafastronomers.

5 Lemaître, Abbé Georges-Édouard(1894–1966)BelgianAstrophysicist, Cosmologist

Georges-Édouard Lemaître was the innovativecosmologist who suggested in 1927 that a violentexplosion might have started an expanding uni-verse. He based this hypothesis on his interpreta-tion of ALBERT EINSTEIN’s general relativity theoryand upon EDWIN POWELL HUBBLE’s contemporaryobservation of galactic redshifts—an observa-tional indication that the universe was indeed ex-panding. Other physicists, such as RALPH ASHER

ALPHER under the direction of GEORGE GAMOW,built upon Lemaître’s pioneering work and devel-oped it into the widely accepted big bang theoryof modern cosmology. Central to Lemaître’s modelis the idea of an initial superdense primeval atom,his “cosmic egg,” that started the universe in acolossal ancient explosion.

Lemaître was born on July 17, 1894, inCharleroi, Belgium. Prior to World War I, hestudied civil engineering at the University ofLouvain. At the outbreak of war in 1914, hevolunteered for service in the Belgian army andearned the Belgian Croix de Guerre for hiscombat activities as an officer in the artillerycorps. Following the war, he returned to theUniversity of Louvain where he pursued addi-tional studies in physics and mathematics. In theearly 1920s he also responded to another voca-tional calling and became an ordained priest inthe Roman Catholic Church in 1923. After

202 Lemaître, Abbé Georges-Édouard

ordination, Abbé Lemaître pursued a careerdevoted to science, especially the area of cos-mology, in which he would make a major 20th-century contribution.

Taking advantage of an advanced studiesscholarship from the Belgian government,Lemaître traveled to England to study (1923–24)with SIR ARTHUR STANLEY EDDINGTON at thesolar physics laboratory of the University ofCambridge. He continued his travels and cameto the United States where he studied at theMassachusetts Institute of Technology (MIT)from 1925–27, earning his Ph.D. in physics.While at MIT, Lemaître became familiar withthe expanding-universe concepts just being de-veloped by the American astronomers HARLOW

SHAPLEY and EDWIN HUBBLE.In 1927 Lemaître returned to Belgium and

joined the faculty of the University of Louvainas a professor of astrophysics, a position he heldfor the rest of his life. That year he published hisfirst major paper related to cosmology. Unawareof similar work by the Russian mathematicianAlexander Friedmann (1888–1925), Lemaîtreblended Einstein’s general relativity and Hubble’searly work on expanding galaxies to reach theconclusion that an expanding-universe model isthe only appropriate explanation for observedredshifts of distant galaxies. Lemaître suggestedthe distant galaxies serve as “test particles” thatclearly demonstrate the universe is in a state ofexpansion. Unfortunately, Lemaître’s importantinsight attracted little attention within the as-tronomical community, mainly because he pub-lished this paper in a rather obscure scientificjournal in Belgium.

But in 1931 Eddington discovered Lemaître’spaper and, with his permission, had the papertranslated into English and then published in theMonthly Notices of the Royal Astronomical Society.Eddington also provided a lengthy commentaryto accompany the translation of Lemaître’s pa-per. By this time Hubble had formally announcedhis famous law (Hubble’s law) that related the

distance of galaxies to their observed redshift.So Lemaître’s paper, previously ignored, nowcreated quite a stir in the astrophysical com-munity. He was invited to come to London tolecture about his expanding-universe concept.During this visit, he not only presented anextensive account of his original theory ofthe expanding universe, he also introducedhis idea about a “primitive atom” (sometimescalled Lemaître’s “cosmic egg”). He was busythinking not only about how to show that theuniverse was expanding but also about whatcaused the expansion and how this great processbegan.

Lemaître cleverly reasoned that if the galax-ies are now everywhere expanding, then in thepast they must have been much closer together.In his mind, he essentially ran time backward tosee what conditions were as the galaxies camecloser and closer together in the early universe.He hypothesized that eventually a point wouldbe reached when all matter resided in a super-dense primal atom. He further suggested thatsum instability within this primal atom wouldresult in an enormous explosion that would startthe universe expanding. Big Bang cosmology re-sults directly from his concepts, although it tookseveral decades to fully develop and establishthe Big Bang theory as the currently preferredcosmological model.

Lemaître’s other significant papers include“Discussion on the Evolution of the Universe”(1933) and “Hypothesis of the Primeval Atom”(1946). His contributions to astrophysics andmodern cosmology were widely recognized. In1934 he received the Prix Francqui (FrancquiAward) directly from the hands of Einstein,who had personally nominated Lemaître forthis prestigious award. In 1936 he became amember of the Pontifical Academy of Sciencesand then presided over this special papal scien-tific assembly as its president from 1960 until hisdeath. In 1941, the Royal Belgian Academy ofSciences and Fine Art voted him membership.

Leverrier, Urbain-Jean-Joseph 203

The Belgian government bestowed its highestaward for scientific achievement upon him in1950, and the British Royal AstronomicalSociety awarded him the society’s first EddingtonMedal in 1953. Lemaître died at Louvain,Belgium, on June 20, 1966. However, he livedlong enough to witness the detection by ARNO

ALLEN PENZIAS and ROBERT WOODROW Wilsonof the microwave remnants of the big bang—anevent he had boldly hypothesized almost fourdecades earlier.

5 Leverrier, Urbain-Jean-Joseph(1811–1877)FrenchAstronomer, Mathematician, OrbitalMechanics Expert

Urbain Leverrier was a skilled celestial mechan-ics practitioner who mathematically predictedin 1846 (independent of JOHN COUCH ADAMS)the possible location of an eighth, as yet unde-tected, planet in the outer regions of the solarsystem. Leverrier sent his calculations to theBerlin Observatory and Neptune was quicklydiscovered by telescopic observation.

Leverrier was born on March 11, 1811, inSaint-Lô, France. His father, a local governmentofficial, made a great financial sacrifice so thathis son could receive a good education at theprestigious École Polytechnique. After gradua-tion, Leverrier began his professional life as achemist. He investigated the nature of certainchemical compounds under the supervision of theFrench chemist Joseph Gay-Lussac (1778–1850),who was a professor of chemistry at the ÉcolePolytechnique. In 1836 Leverrier accepted anappointment as a lecturer in astronomy at thesame institution. Consequently, with neitherprevious personal interest in nor extensiveformal training for astronomy, Leverrier sud-denly found himself embarking on an astro-nomically oriented academic career. The process

all came about rather quickly, when the oppor-tunity for academic promotion at the ÉcolePolytechnique presented itself and Leverrierseized the moment.

As he settled into this new academic posi-tion, Leverrier began investigating lingeringissues in celestial mechanics. He decided to fo-cus his attention on continuing the work ofPIERRE-SIMON MARQUIS DE LAPLACE in mathe-matical astronomy and demonstrate with evenmore precision the inherent stability of the so-lar system. Following the suggestion given him

In 1846 the French celestial mechanics practitionerUrbain J. J. Leverrier mathematically predicted thelocation of the planet Neptune so well that theGerman astronomer Johann Galle was able to quicklydiscover Neptune by telescopic observation on theevening of September 23 of that year. Leverrier’scomputational effort, accomplished independently ofJohn Couch Adam’s, is considered to be one of thegreat triumphs of mathematical astronomy in the 19thcentury. (Courtesy of NASA)

204 Leverrier, Urbain-Jean-Joseph

in 1845 by DOMINIQUE-FRANÇOIS-JEAN ARAGO,he began investigating the subtle perturbationsin the orbital motion of Uranus, the outerplanet discovered by SIR WILLIAM HERSCHEL

some 50 years prior. In 1846 Leverrier, follow-ing the suggestions of other astronomers(among them FRIEDRICH WILHELM BESSEL), hy-pothesized that an undiscovered planet lay be-yond the orbit of Uranus. He then examinedthe perturbations in the orbit of Uranus andused the law of gravitation to calculate theapproximate size and location of this outerplanet. Unknown to Leverrier, the British as-tronomer Adams had made similar calcula-tions. However, during this period, Sir GeorgeBiddell Airy (1801–92), Britain’s AstronomerRoyal, basically ignored Couch’s calculationsand correspondence about the possible locationof a new outer planet.

In mid-September 1846 Leverrier sent a de-tailed letter to the German astronomer JOHANN

GOTTFRIED GALLE at the Berlin Observatorytelling Galle where to look in the night sky fora planet beyond Uranus. On the evening ofSeptember 23, 1846, Galle found Neptune af-ter about an hour of searching. The French-German team of mathematical and observa-tional astronomers had beaten the Britishastronomical establishment to one of the 19thcentury’s greatest discoveries. In France Leverrierexperienced the celebrity that often accompa-nies a widely recognized scientific accomplish-ment. He received appointment to a speciallycreated chair of astronomy at the University ofParis, and the French government made himan officer in the Legion of Honor. Leverrierreceived international credit for mathematicaldiscovery of Neptune, which was immediatelyfollowed by controversy. The Royal Society ofLondon awarded him its Copley Medal in1846 and elected him a Fellow in 1847. As apoint of scientific justice, Adams received theCopley Medal in 1848 for his discovery ofNeptune.

Bristling with success, fame, and good for-tune, Leverrier pressed his luck in 1846 by ap-plying mathematical astronomy to explain mi-nor perturbations in the solar system. This time,he looked inward at the puzzling behavior in theorbital motion of Mercury, the innermost knownplanet. Unfortunately, Leverrier failed quitemiserably with his hypothesis that the observedperturbations in Mercury were due to the pres-ence of an inner undiscovered planet he calledVulcan, or possibly even a belt of asteroids or-biting closer to the Sun. Many 19th-centuryobservational astronomers, including SAMUEL

HEINRICH SCHWABE, searched in vain forVulcan. ALBERT EINSTEIN’s general relativitytheory in the early part of the 20th century ex-plained the perturbations of Mercury without re-sorting to Leverrier’s hypothetical planet.

In 1854 Leverrier succeeded Arago as thedirector of the Paris Observatory, founded in1667 by King Louis XIV who appointedGIOVANNI DOMENICO CASSINI as its first direc-tor. This observatory served as the national ob-servatory of France and was the first such na-tional observatory established in the era oftelescopic astronomy. Leverrier focused his ef-forts from 1847 until his death on producingmore accurate planetary data tables and oncreating a set of standard references for use byastronomers.

Unfortunately, Leverrier was an extremelyunpopular director, who ran the Paris Observatorylike a tyrant. By 1870 his coworkers had hadenough and he was replaced as director. However,he was reinstated to the directorship in 1873when his successor, Charles-Eugene Delaunay(1816–72) died suddenly. This time, however, heserved under the very watchful authority of a di-recting council.

Leverrier died in Paris on September 23,1877. His role in celestial mechanics and thepredictive discovery of Neptune represents oneof the greatest triumphs of mathematical as-tronomy.

Lippershey, Hans 205

5 Lippershey, Hans (Hans Lippersheim, Jan Lippersheim)(ca. 1570–ca. 1619)DutchOptician

Hans Lippershey is the Dutch optician generallycredited with the invention of the telescope, be-cause he was the first among his contemporariesto attempt to patent a simple, two-lens viewinginstrument in 1608. However, once news ofthis new type of optical instrument circulatedthrough western Europe, creative persons suchas GALILEO GALILEI and JOHANNES KEPLER

quickly recognized the telescope’s important rolein observational astronomy and spearheaded alitany of design improvements that continues upto modern times.

The Dutch lens maker (optician) Lippersheywas born in approximately the year 1570 inthe town of Wesel, Germany. He moved toMiddelburg, the capital city of the province ofZeeland, in what is now the modern Kingdomof the Netherlands. Practicing his craft as a lensand spectacle-maker, he married there in 1594,and became a citizen. At the time, Middelburgwas a prosperous city experiencing an influx ofDutch Protestant refugees who were fleeing fromthe Spanish invasion of the southern provincesof the Netherlands (now modern Belgium). Inthe late 16th century this region, like much ofwestern Europe, was in a state of political andreligious turmoil. The Dutch people living innorthern provinces of the region known as theSeventeen Provinces of the Netherlands hadembraced Protestantism and were striving formore political freedom from the Catholic kingof Spain. Through the Union of Utrecht (1579),William the Silent, prince of Orange, led a con-federation of seven northern provinces calledestates (Holland, Zeeland, Utrecht, Gelderland,Overrijssel, Groningen, and Friesland). The es-tates retained individual sovereignty, but wererepresented jointly in the States-General, a

governing political body that had control offoreign affair and defense. By 1581 the estatesrepudiated allegiance to Spain and formed theRepublic of the Seven United Netherlands—thenucleus of the Dutch republic that grew into a17th-century naval and economic power.

Several historic anecdotes describe how thetelescope came into being. Hans Lippersheygenerally appears at the center of most of thesestories by virtue of his being the first person toactually apply for a patent for a kijker, or “looker.”One of the most popular stories suggests that anapprentice in Lippershey’s lens-making shop wastinkering with various arrangements of lensesand noticed that a special combination twoshort-focus convex lenses placed at the oppositeends of a long tube would make distant objectsappear nearer. Lippershey immediately realizedthe potential military significance of this deviceand applied for a patent from the States-Generalthrough the local government of Zeeland.

The oldest surviving record concerning theinvention of the telescope is a letter, datedSeptember 25, 1608, from the government ofthe Estate of Zeeland to the States-General of theSeven United Netherlands, requesting that theStates-General assist the bearer of the letter(Lippershey) “who claims to have a certain de-vice by means of which all things at a very greatdistance can be seen as if they were nearby.”Members of the States-General discussedLippershey’s patent application on October 2,1608, and then denied the application, statingthat the basic concept for such a device couldnot be kept secret.

Members of the assembly were quite correcton this point. Upon learning about the Dutchtelescope from his son, Galileo immediatelyfashioned his own devices in 1609, looked intothe night sky, and started the field of telescopicastronomy. However, the States-General of theSeven Netherlands did reward Lippershey for hisefforts. The governing body awarded him a gen-erous fee (900 florins) to modify his telescope

206 Lockyer, Sir Joseph Norman

into a binocular device, which they consideredmore practical for military applications.

Other Dutch lens makers also claimed creditfor inventing the telescope. As the States-General was reviewing Lippershey’s patent re-quest, another patent request arrived from JacobMetius (1580–1628), an instrument maker fromAlkmaar, a city in the northern part of theNetherlands. Metius sought a patent for his “per-spicilla” in October 1608, barely two weeks af-ter Lippershey initiated his request. Several yearslater, Zacharias Janssen (1580–ca. 1638), an-other Dutch optician from Middelburg, claimedcredit for inventing the telescope. At this point,on the basis of surviving historic records, it isimpossible to establish exactly who really “in-vented” the telescope or precisely when thecreative moment took place. Lippershey holdsthe favored position because his request forpatent is the oldest surviving record of the pe-riod. Sometime in 1619, he died in Middelburg.

5 Lockyer, Sir Joseph Norman(1836–1920)BritishPhysicist, Astronomer, Spectroscopist

Helium is the second most abundant element inthe universe, yet its existence was totally un-known prior to the late 19th century. In 1868the British physicist Sir Joseph Norman Lockyercollaborated with the French astronomer Pierre-Jules-César Janssen (1824–1907) and discoveredthe element helium through spectroscopic stud-ies of solar prominences. However, it was not un-til 1895 that the Scottish chemist Sir WilliamRamsay (1852–1916) finally detected the gas inEarth’s atmosphere. Lockyer also founded theprestigious scientific periodical Nature and pio-neered the field of archaeological astronomy.

Lockyer was born on May 17, 1836, inRugby, England. Following a traditional post-secondary education outside of Great Britain on

the European Continent, Lockyer began a careeras a civil servant in the War Office of the Britishgovernment. While serving in this capacityfrom approximately 1857–69, he also becamean avid amateur astronomer, enthusiasticallypursuing this scientific hobby in every spare mo-ment. Following observation of a solar eclipsein 1858, he constructed a private observatory athis home. In 1861 while working at the WarOffice in London, he married and settled inWimbledon. Lockyer made several important as-tronomical discoveries in the 1860s and turnedto astronomy and science on a full-time basis atthe end of that decade.

While still an amateur astronomer in the1860s, Lockyer decided to apply the emergingfield of spectroscopy to study the Sun. This de-cision enabled Lockyer to join two other earlyastronomical spectroscopists, Janssen and SIR

WILLIAM HUGGINS, in extending the pioneeringwork of ROBERT WILHELM BUNSEN and GUSTAV

ROBERT KIRCHHOFF. Lockyer’s efforts directlycontributed to development of modern astro-physics. In 1866 he started spectroscopic obser-vation of sunspots. He observed Doppler shiftsin their spectral lines and suggested that strongconvective currents of gas existed in the outerregions of the Sun—a region he named thechromosphere.

By 1868 he devised a clever method ofacquiring the spectra of the solar prominenceswithout waiting for an eclipse of the Sun to takeplace. A prominence is a cooler, cloudlike fea-ture found in the Sun’s corona. Prominencesoften appear around the Sun’s limb during totalsolar eclipses. Lockyer discovered that he couldobserve the spectra of prominences withouteclipse conditions if he passed light from thevery edge of the Sun through a prism.

Almost simultaneously, but independent ofLockyer, the French astronomer Janssen also de-veloped this method of obtaining the spectra ofsolar prominences. Janssen and Lockyer reportedtheir identical discoveries at the same meeting

Lockyer, Sir Joseph Norman 207

of the French Academy of Sciences. Officials ofthe academy wisely awarded, 10 years later, bothmen a special “joint medallion” to honor theirsimultaneous and independent contribution tosolar physics.

In 1868 Janssen used his newly developedspectroscopic technique to investigate promi-nences during a solar eclipse expedition toGuntur, India. Janssen reported an unknownbright orange line in the spectral data he col-lected. Lockyer reviewed Janssen’s report andthen compared the position of the reported un-known orange line to the spectral lines of all theknown chemical elements. When he could notfind any correlation, Lockyer concluded that thisline was the spectral signature of a yet undis-covered element. He named the element he-lium, after Helios, the sun god in Greekmythology. Because spectroscopy was still in itsinfancy, most scientists waited for almost threedecades before accepting Lockyer’s identificationof a new element in the Sun. Wide scientific ac-ceptance of Lockyer’s discovery of helium tookplace only after Ramsay detected the presenceof this elusive gas within Earth’s atmospherein 1895.

In 1869 Lockyer won election as a fellow tothe Royal Society. He decided to abandon hiscivil service career so he could pursue astron-omy and science full time. That year he foundedthe internationally acclaimed scientific journalNature; he would serve as its editor for almost 50years. Between 1870 and 1905, Lockyer remainedan active solar astronomer and personally partici-pated in eight solar eclipse expeditions.

In 1873 Lockyer turned his attention to stel-lar spectroscopy and introduced his theory ofatomic and molecular dissociation in an attemptto explain puzzling green lines in the spectra ofcertain nebulas. He disagreed with fellow Britishspectroscopist Huggins who suggested that thegreen lines came from an unknown element hecalled “nebulium.” Instead, Lockyer hypothe-sized that they might actually be from terrestrial

compounds that had dissociated into unusualcombinations of simpler substances, makingtheir spectral signatures unrecognizable. AnAmerican astrophysicist, Ira Bowen (1898–1973)solved the mystery of “nebulium” in the 1920s,when he demonstrated that the green emissionlines from certain nebulas were actually causedby forbidden electron transitions taking place inoxygen and nitrogen under various excited statesof ionization. Lockyer’s theory of dissociationwas definitely on the right track.

Lockyer was an inspiring lecturer. In 1881he developed an interesting new course in as-trophysics at the Royal College of Science (to-day part of the Imperial College). By 1885 hereceived an academic promotion to professor ofastrophysics, making him the world’s first pro-fessor in this discipline. The Royal College alsoconstructed the Solar Physics Observatory atKensington to support his research and teachingactivities. Lockyer served as the observatory’s di-rector until approximately 1913, when the fa-cility moved to a new location at CambridgeUniversity.

During travel to Greece and Egypt in theearly 1890s, Lockyer noticed how many ancienttemples had their foundations aligned along aneast-west axis—a consistent alignment that sug-gested to him some astronomical significancewith respect to the rising and setting Sun. Topursue this interesting hypothesis, Lockyer vis-ited Karnack, one of the great temples of ancientEgypt. He discussed the hypothesis in his 1894book, The Dawn of Astronomy. This book is of-ten regarded as the beginning of archaeologicalastronomy—the scientific investigation of theastronomical significance of ancient structuresand sites.

As part of this effort, Lockyer studiedStonehenge, an ancient site located in southEngland. However, he could not accurately de-termine the site’s construction date. As a result,he could not confidently project the solar cal-endar back to a sufficiently precise moment in

208 Lowell, Percival

history that would reveal how the curious cir-cular ring of large vertical stones topped bycapstones might be connected to some astro-nomical practice of the ancient Britons.Lockyer’s visionary work clearly anticipated theresults of modern studies of Stonehenge—resultsthat suggest the site could have served as an an-cient astronomical calendar around 2000 B.C.E.

Lockyer was a prolific writer. His best-knownpublished works include Studies in SpectrumAnalysis (1872), The Chemistry of the Sun (1887),and The Sun’s Place in Nature (1897). In 1874the Royal Society of London recognized hisimportant achievements in solar physics andastronomical spectroscopy and awarded him itsRumford Medal.

In 1897 Lockyer joined the Order of KnightCommander of the Bath (KCB), a royal honorbestowed upon him by Britain’s Queen Victoriafor his discovery of helium and lifetime contri-butions to science. After the Solar PhysicsObservatory at the Royal College was movedfrom Kensington to Cambridge University, SirLockyer remained active in astronomy by con-structing his own private observatory in 1912 inSidmouth, Devonshire. This facility, called theNorman Lockyer Observatory, currently oper-ates under the supervision of an organization ofamateur astronomers.

Lockyer, the British civil servant who en-tered astronomy in the 1850s as a hobby andbecame one of the great pioneers in astrophysicsand stellar spectroscopy, died on August 16,1920, at Salcombe Regis, Devonshire.

5 Lowell, Percival(1855–1916)AmericanAstronomer

Late in the 19th century Percival Lowell estab-lished a private astronomical observatory, theLowell Observatory, near Flagstaff, Arizona,

primarily to support his personal interest inMars and his aggressive search for signs of anintelligent civilization there. Driving Lowellwas his misinterpretation of GIOVANNI VIRGINIO

SCHIAPARELLI’s use of the word canali in an 1877technical report in which the Italian astronomerdiscussed his telescopic observations of theMartian surface. Lowell took this report as earlyobservational evidence of large, water-bearingcanals built by intelligent beings. Lowell wrotebooks, such as Mars and Its Canals (1906) andMars As the Abode of Life (1908) to commu-nicate his Martian civilization theory to thepublic. While his nonscientific (but popular)interpretation of observed surface features onMars proved quite inaccurate, his astronomicalinstincts were correct for another part of the so-lar system. Based on perturbations in the orbitof Neptune, Lowell predicted in 1905 the exis-tence of a planet-sized, trans-Neptunian object.In 1930 CLYDE WILLIAM TOMBAUGH, working atthe Lowell Observatory, discovered Lowell’sPlanet X and called the tiny planet Pluto.

Lowell was born on March 13, 1855, inBoston, Massachusetts, into an independentlywealthy family. His brother Abbott Lowell be-came president of Harvard University and hissister Amy became an accomplished poet.Following graduation with honors from HarvardUniversity in 1876, Lowell devoted his time tobusiness and to traveling throughout the FarEast. Based on his experiences between 1883 and1895, Lowell published several books about theFar East, including: Chosön (1886), The Soul ofthe Far East (1888), Noto (1891) and OccultJapan (1895).

He was not especially attracted to astron-omy until later in life, when he discovered anEnglish translation of Schiaparelli’s 1877 Marsobservation report that presented the Italian wordcanali. As originally intended by Schiaparelli,canali simply meant “channels.” In the early1890s Lowell unfortunately became erroneouslyinspired by the thought of artificially constructed

Lowell, Percival 209

canals on Mars, the presence of which he thenextended to imply the existence of an advancedalien civilization. From this point on, Lowelldecided to become an astronomer and dedicatehimself to a detailed study of Mars.

Unlike other observational astronomers,however, Lowell was independently wealthy andalready had a general idea of what he was search-ing for—evidence of an advanced civilization ofthe Red Planet. To support this quest, he sparedno expense and sought the assistance of profes-sional astronomers. William Henry Pickering(1858–1938) from the Harvard College Obser-vatory, and his assistant ANDREW ELLICOTT

DOUGLASS helped Lowell find an excellent “see-ing” site upon which to build a private observa-tory for the study of Mars, which Lowellconstructed near Flagstaff, Arizona. Called theLowell Observatory, it was opened in 1894 andhoused a top quality 24-inch refractor telescopethat allowed Lowell to perform some excellentplanetary astronomy. However, his “observations”tended to anticipate the things he reported, likeoases and seasonal changes in vegetation. Otherastronomers, including Douglass, would labelthese blurred features simply indistinguishablenatural markings. As Lowell more aggressivelyembellished his Mars observations, Douglassbegan to question Lowell’s interpretation of thesedata. Perturbed by Douglass’s scientific challenge,Lowell simply fired him in 1901 and then hiredVesto M. Slipher to fill the vacancy.

In 1902 the Massachusetts Institute ofTechnology (MIT) gave Lowell an appointmentas a nonresident astronomer. He was definitelyan accomplished observer, but often could notresist the temptation to greatly stretch his in-terpretation of generally fuzzy and opticallydistorted surface features on Mars into observa-tional evidence of artifacts from an advancedcivilization. With such books as Mars and ItsCanals Lowell became popular with the generalpublic, which drew excitement from his specu-lative (but scientifically unproven) theory of an

intelligent civilization on Mars struggling to dis-tribute water from the planet’s polar regions witha series of elaborate giant canals. While mostplanetary astronomers shied away from such un-founded speculation, science fiction writersflocked to Lowell’s hypothesis—a premise thatsurvived in various forms until the dawn of theSpace Age. On July 14, 1965, NASA’s Mariner4 spacecraft flew past the Red Planet and re-turned images of its surface that shattered all pre-vious speculations and romantic myths about aseries of large canals built by a race of ancientMartians.

Since the Mariner 4 encounter with Mars,an armada of other robot spacecraft have alsostudied Mars in great detail. No cities, canals,nor intelligent creatures have been found on theRed Planet. What has been discovered, however,is an interesting “halfway” world. Part of theMartian surface is ancient, like the surfaces ofthe Moon and Mercury, while part is moreevolved and Earthlike. In the 21st century, ro-bot spacecraft and eventually human explorerswill continue Lowell’s quest for Martians—butthis time they will hunt for tiny microorgan-isms possibly living in sheltered biologicalniches or else possible fossilized evidence of an-cient Martian life-forms from the time whenthe Red Planet was a milder, kinder and wetterworld.

While Lowell’s quest for signs of intelligentlife on Mars may have lacked scientific rigor bya considerable margin, his astronomical instinctsabout “Planet X”—his name for a suspected icyworld lurking beyond the orbit of Neptune—proved technically correct. In 1905 Lowell be-gan to make detailed studies of the subtle per-turbations in Neptune’s orbit and predicted theexistence of a planet-sized trans-Neptunianobject. He then began an almost decade-longtelescopic search, but he failed to find this elu-sive object. In 1914, near the end of his life,he published the negative results of his search forPlanet X and bequeathed the task to some future

210 Lowell, Percival

astronomer. Lowell died in Flagstaff, Arizona, onNovember 12, 1916.

In 1930, Tombaugh, a farm boy turned am-ateur astronomer, fulfilled Lowell’s quest. Hiredby Slipher to work as an observer at the LowellObservatory and search for Planet X, Tombaughmade use of the blinking comparator techniqueto find the planet Pluto on February 18, 1930.The Lowell Observatory still functions today as

a major private astronomical observatory. An of-ten forgotten milestone in astronomy took placeat the Lowell Observatory in 1912, when Sliphermade early measurements of the Doppler shift ofdistant nebulas. He found many to be recedingfrom Earth at a high rate of speed. Slipher’s workprovided EDWIN POWELL HUBBLE the basic di-rection he needed to discover the expansion ofgalaxies.

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M5 Messier, Charles

(1730–1817)FrenchAstronomer

Charles Messier, the first French astronomer tospot comet Halley during its anticipated returnin 1758, was an avid “comet hunter.” He per-sonally discovered at least 13 new comets andassisted in the codiscovery of at least six others.In 1758 he began compiling a list of nebulasand star clusters that eventually became thefamous noncomet Messier Catalogue. He assem-bled this list of “unmoving” fuzzy nebulas andstar clusters primarily as a tool for astronomersengaged in comet searches.

Messier was born in Badonviller, Lorraine,France, on June 26, 1730. His father died whenMessier was a young boy and the family wasthrust into poverty. The appearance of a multi-tailed comet and the solar eclipse of 1748 stim-ulated his childhood interest in astronomy.Messier went to Paris in 1751 and became a clerkfor Joseph Nicolas Delisle (1688–1768), whowas then the astronomer of the French navy.Messier’s ability to carefully record data attractedDelisle’s attention, and soon the young clerk wascataloging observations made at Hôtel de Cluny,including the transit of Mercury in May 1753.Delisle, like many other astronomers, anticipated

the return of comet Halley sometime in 1758 andmade his own calculations in an attempt to bethe first to detect its latest visit.

Delisle assigned the task of searching forHalley’s comet to his young clerk. Messier searcheddiligently throughout 1758 but mostly in thewrong location, because Delisle’s calculationswere in error. However, in August of that year,Messier discovered and tracked a different cometfor several months. He detected a distant fuzzyobject that he thought was the anticipatedcomet Halley. However, to Messier’s frustration,the object did not move, so he realized it had tobe a nebula. On September 12, 1758, he care-fully noted its position in his observation log.This particular “fuzzy patch” was actually theCrab Nebula—a fuzzy celestial object previouslydiscovered by another astronomer.

Cometography, that is, “comet hunting,”was one of the great triumphs of 18th-centuryastronomy. Messier enjoyed the thrill and ex-citement that accompanied a successful questfor a new “hairy star”—the early Greek name(κοµετεζ) for a comet. The young clerk-astronomer also realized that fuzzy nebulas andstar clusters caused time-consuming false alarms.He had the solution—prepare a list of noncometobjects, such as nebulas and star clusters. In the18th century, astronomers used the word nebulato describe any fuzzy, blurry, luminous celestial

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object that could not be sufficiently resolved byavailable telescopes. The fuzzy object he mistookfor a comet in late August 1758 eventually be-came object number one (M1) in the MessierCatalogue—namely, the great Crab Nebula inthe constellation Taurus.

Despite false alarms caused by nebulas andhis discovery of another comet, Messier kept vig-orously searching for comet Halley throughout1758. Then, on the evening of December 25,Christmas Day, an amateur German astronomernamed Georg Palitzch became the first observerto catch a glimpse of the greatly anticipatedcomet, as it returned to the inner portions of thesolar system. About a month later, on theevening of January 21, 1759, Messier succeededin viewing this comet and became the firstFrench astronomer to have successfully done soduring the comet’s 1758–59 journey throughperihelion. His work earned him recognition atthe highest levels. The French king Louis XVfondly referred to Messier as “the comet ferret.”

After the passage of comet Halley, Messiercontinued to search for new comets and to as-semble his noncomet list of nebulas and star clus-ters. By 1764 this list contained 40 objects, 39 ofwhich he personally verified through his own ob-servations. Within the resolution limits of thetelescopes of his day, Messier’s objects includednebulas, star clusters, and distant galaxies.

By 1771 he had completed the first versionof his famous noncomet list and published it asthe Catalogue of Nebulae and of Star Clusters in1774. This initial catalog contained 45 Messierobjects. He completed the final version of hisnoncomet list of celestial objects in 1781. It con-tained 103 objects (seven additional wereadded later) and was published in 1784. Messierdesignated each of the entries in the list by aseparate number, prefixed by the letter M. Forexample, Messier object M1 represented theCrab Nebula, and object M31 represented theAndromeda Galaxy. His designations persist tothe present day, although the Messier designa-

tions have generally been superseded by thedesignations presented in the New GeneralCatalogue of Nebulae and Clusters of Stars (NGC)published in 1888 by the Danish astronomerJohan Dreyer (1852–1926).

In 1764 Messier was elected as a foreignmember of the Royal Society of London. In 1770he became a member of the Paris Academy ofSciences, and the astronomer of the Frenchnavy, officially assuming the position formerlyheld by Delisle, who had retired six years earlier.However, Messier lost this position during theFrench Revolution and his observatory at theHôtel de Cluny fell into general disrepair.

In 1806 Napoleon Bonaparte (1769–1821)awarded Messier the cross of the Legion ofHonor—possibly because Messier had openlyand rather unscientifically suggested in a tech-nical paper that the appearance of the greatcomet of 1769 correlated with Napoleon’s birth.This politically inspired act of astrology is thelast known attempt by an otherwise knowledge-able astronomer to tie the appearance of a cometto a significant historic event on Earth. Messierdied in Paris on April 11, 1817. Most of thecomets he so eagerly sought have been forgot-ten, but his famous noncomet list of celestial ob-jects serves as a permanent tribute to one of the18th century’s most successful “comet hunters.”

5 Michelson, Albert Abraham(1852–1931)German/AmericanPhysicist

How fast does light travel? Physicists have pon-dered that challenging question since GALILEO

GALILEI’s time. In the late 1880s Albert Michelsonprovided the first very accurate answer—a ve-locity slightly less than 300,000 kilometers persecond. He received the 1907 Nobel Prize inphysics for his innovative optical measurementsand precision measurements.

Michelson, Albert Abraham 213

study advanced optics in Europe. In Germanyhe visited the University of Berlin and the Uni-versity of Heidelberg. He also studied at theCollège de France and the École Polytechniquein Paris. In 1881 he resigned from the U.S. Navyand then returned to the United States to ac-cept an appointment as a professor of physicsat the Case School in Applied Science inCleveland, Ohio. Michelson had conducted somepreliminary experiments in measuring the speedof light in 1881 at the University of Berlin. Oncesettled in at Case, he refined his experimentaltechniques and obtained a value of 299,853 kilo-meters per second. This value remained a stan-dard within physics and astronomy for more thantwo decades and changed only when Michelsonhimself improved the value in the 1920s.

In the early 1880s, with financial supportfrom the Scottish-American inventor AlexanderGraham Bell (1847–1922), Michelson con-structed a precision optical interferometer—aninstrument that splits a beam of light into twopaths and then reunites the two separate beams.Should either beam experience travel across dif-ferent distances or at different velocities (due topassage through different media), the reunitedbeam would appear out of phase and produce adistinctive arrangement of dark and light bandscalled an interference pattern. Using an inter-ferometer in 1887, Michelson collaboratedwith the American physicist William Morley(1838–1923) to perform one of the most im-portant “failed” experiments ever undertaken inscience.

Now generally referred to as the Michelson-Morley experiment, this experiment used an in-terferometer to test whether light traveling inthe same direction as Earth through space movesmore slowly than light traveling at right anglesto Earth’s motion. Their failure to observe ve-locity differences in the perpendicular beams oflight dispelled the prevailing concept that lighttraveled through the universe using some sort ofinvisible “cosmic ether” as the medium. Michelson

Michelson was born in Strelno, Prussia (nowStrzelno, Poland) on December 19, 1852. Whenhe was two years old, his family immigrated tothe United States, settling first in Virginia City,Nevada, and then in San Francisco, California,where he received his early education. In 1869Michelson received an appointment fromPresident Grant to the U.S. Naval Academy inAnnapolis, Maryland. More skilled as a scientistthan as a seaman, he graduated from Annapolisin 1873 and received his commission as an en-sign in the U.S. Navy. Following two years ofsea duty, Michelson became an instructor inphysics and chemistry at the academy, then in1879 an assignment to the navy’s NauticalAlmanac Office in Washington, D.C. There hemet and worked with SIMON NEWCOMB who,among many other things, was attempting tomeasure the velocity of light.

After about a year at the Nautical AlmanacOffice, Michelson took a leave of absence to

The Nobel laureate Albert Michelson had a lifelongpassion for precision optical instruments (like the typehe is inspecting in the photograph) and extremelyaccurate measurements of the velocity of light. Hewas the first American scientist to receive a NobelPrize in physics and experienced this great honor in1907 for his innovative optical experiments andprecision measurements. (AIP Emilio Segrè VisualArchives)

214 Michelson, Albert Abraham

pathway between two mountain peaks in Californiathat he had carefully surveyed to an accuracy ofless than 2.5 centimeters. With a specially de-signed revolving eight-sided mirror, he measuredthe velocity of light as 299,798 kilometers persecond. After retiring from the University ofChicago in 1929, Michelson joined the staff ofthe Mount Wilson Observatory in California. Inthe early 1930s he bounced light beams back andforth in an evacuated tube to produce an ex-tended 16-kilometer pathway to measure opticalvelocity in a vacuum. The final result, an-nounced in 1933, after his death, was a velocityof 299,794 kilometers per second. To appreciatethe precision of Michelson’s work, the currentlyaccepted value of the velocity of light in a vac-uum is 299,792.5 kilometers per second.

Michelson died in Pasadena, California, onMay 9, 1931. His most notable scientific worksinclude Velocity of Light (1902), Light Waves andTheir Uses (1899–1903) and Studies in Optics(1927). In addition to being the first Americanscientist to win a Nobel Prize, Michelson re-ceived numerous other awards and internationalrecognition for his contributions to physics. Hebecame a member (1888) and served as presi-dent of (1923–27) the American NationalAcademy of Sciences. The Royal Society ofLondon made him a foreign Fellow in 1902and presented him its Copley Medal in 1907.He also received the Draper Medal from theAmerican National Academy of Sciences in1912, the Franklin Medal from the FranklinInstitute in Philadelphia in 1923, and the GoldMedal of the Royal Astronomical Society in1923. His greatest scientific accomplishmentwas the accurate measurement of the velocityof light—a physical “yardstick” of the universeand an important constant throughout all ofmodern physics.

had reasoned that when rejoined in the inter-ferometer the two beams of light should be outof phase due to Earth’s motion through the pos-tulated ether. But their very careful measure-ments failed to detect any interfering influenceof the hypothetical, all-pervading ether. Ofcourse, the real reason their classic experimentfailed is now very obvious—there isn’t any “cos-mic ether.” Michelson’s work was exact, precise,and provided a very correct, albeit null, result.The absence of ether gave ALBERT EINSTEIN im-portant empirical evidence upon which he con-structed his special relativity theory in 1905.The Michelson-Morley experiment provided thefirst direct evidence that light travels at a con-stant speed in space—the very premise uponwhich all of special relativity is built.

From 1889 to 1892 Michelson served as aprofessor of physics at Clark University inWorcester, Massachusetts. He then left ClarkUniversity to accept a position in physics in thenewly created University of Chicago. He re-mained affiliated with this university until hisretirement in 1929. In 1907 Michelson becamethe first American scientist to receive the NobelPrize in physics. He received this distinguishedinternational award because of his excellence inthe development and application of precisionoptical instruments.

During World War I, he rejoined the U.S.Navy. Following this wartime service, Michelsonreturned to the University of Chicago and turnedhis attention to astronomy. Using a sophisticatedimprovement of his optical interferometer, hemeasured the diameter of the star Betelgeuse in1920. His achievement represented the first ac-curate determination of the size of a star, ex-cluding the Sun. In 1923 he resumed his lifelongquest to improve the measurement of the velocityof light. This time he used a 35-kilometer-long

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N5 Newcomb, Simon

(1835–1909)Canadian/AmericanAstronomer, Mathematician

Simon Newcomb was one of the 19th century’sleading mathematical astronomers. While work-ing for the Nautical Almanac Office of the U.S.Naval Observatory, he prepared extremely ac-curate tables that predicted the position of solarsystem bodies. Before the arrival of navigationsatellites, sailors found their way at sea using anaccurate knowledge of the positions of naturalcelestial objects, such as the Sun, the Moon, andother planets. The more accurate the availablenautical tables, the more precisely sea captainscould chart their voyages. In 1860 Newcombpresented a trend-busting astronomical paper inwhich he correctly speculated that the main-beltasteroids did not originate from the disinte-gration of a single ancient planet, as was thencommonly assumed.

Newcomb was born on March 12, 1835, inWallace, Nova Scotia, Canada. As the son ofan itinerant teacher, he received little formalschooling, and what education he did experiencein childhood took place privately. Newcombmoved to the United States in 1853 and, muchlike his father, worked as a teacher in Marylandbetween 1854 and 1856. While proximate to the

libraries in Washington, D.C., Newcomb beganto study mathematics extensively on his own. By1857 Newcomb’s mathematical aptitude caughtthe attention of the great American physicistJoseph Henry (1797–1878), who helped himfind employment as a computer (that is, a per-son who does precise astronomical calculations)at the U.S. Nautical Office, then located atHarvard University in Cambridge, Massachusetts.In 1858 Newcomb graduated from HarvardUniversity with a bachelor of science degree; hecontinued there for three years afterward as agraduate student.

Newcomb received an appointment as aprofessor of mathematics for the U.S. Navy in1861 and was assigned to duty at the U.S. NavalObservatory in Washington, D.C. A year earlierhe had made his initial mark on mathematicalastronomy when he presented a paper demon-strating that the orbits of the asteroids (minorplanets) did not diverge from a single point. Hiscareful calculations dismantled the then-popularhypothesis in solar system astronomy that themain belt of minor planets between Mars andJupiter was the remnants of a single ancientplanet that tore itself apart. Unfortunately,Newcomb’s interesting paper was quickly over-shadowed by the start of the Civil War in April1861 and the pressing needs of the U.S. Navyfor more accurate nautical charts.

216 Newcomb, Simon

At the U.S. Naval Observatory, Newcombfocused all his mathematical talents and ener-gies on preparing the most accurate nauticalcharts ever made (before the era of electroniccomputers). One of his first major responsibili-ties was to negotiate the contract for the Naval

Observatory’s new 26-inch telescope, which hadrecently been authorized by Congress. Newcombalso planned the tower and dome, and supervisedconstruction. Later, he assisted in the develop-ment of the Lick Observatory in California.

Although primarily a mathematical astro-nomer rather than a skilled observer, Newcombparticipated in a number of astronomical expe-ditions while serving the U.S. Naval Observatory.He traveled to Gibraltar in 1870–71 to observean eclipse of the Sun and to the Cape of GoodHope, at the southern tip of Africa, in 1882 toobserve a transit of Venus. In 1877 he receivedpromotion to senior professor of mathematics inthe U.S. Navy (a position with the equivalentnaval rank of captain) and was in charge of theoffice of an important publication, the AmericanEphemeris and Nautical Almanac. Newcomb hada number of military and civilian assistantshelping him produce the Nautical Almanac, in-cluding ASAPH HALL, the American astronomerwho discovered the two tiny moons of Mars in1877 while a staff member at the U.S. NavalObservatory.

By the 1890s, as American naval powerreached around the globe, Newcomb supportedits needs for improved navigation by producingthe highest-quality nautical almanac yet devel-oped. To accomplish this, he supervised a largestaff of astronomical computers (that is, humanbeings) and enjoyed control of the largest ob-servatory budget in the world. To support theproduction of a high-quality Nautical Almanac,Newcomb pursued, produced, and promoted anew and more accurate system of astronomicalconstants that became the world standard by1896. He retired from his position as superin-tendent of the U.S. Nautical Almanac Office in1897 and received promotion to the rank of rearadmiral in 1905.

Newcomb was also a professor of mathemat-ics and astronomy at Johns Hopkins Universitybetween 1884 and 1893. He served as editor ofthe American Journal of Mathematics for many years

This photograph shows one of the 19th century’sleading mathematical astronomers, Simon Newcomb,at his desk. As the superintendent of the AmericanNautical Almanac Office until his retirement in 1897,Newcomb prepared extremely accurate tables thatpredicted the position of solar system bodies. Hisefforts led to a global standardization of astronomicalreference data and supported great improvements innavigation at sea. (AIP Emilio Segrè Visual Archives,W. F. Meggers Gallery of Nobel Laureates)

Newton, Sir Isaac 217

and as president of the American MathematicalSociety from 1897–98. He was a founding mem-ber and the first president (1899–1905) of theAmerican Astronomical Society.

He wrote numerous technical papers, in-cluding “An Investigation of the Orbit of Uranus,with General Table of Its Motion” (1874) and“Measurement of the Velocity of Light” (1884)—a paper that brought him in contact with a bril-liant young scientist named ALBERT ABRAHAM

MICHELSON. A gifted writer, Newcomb publishedbooks on various subjects for audiences of vary-ing levels, including Popular Astronomy (1877),Principles of Political Economy (1886), and Calculus(1887).

As a gifted mathematical astronomer, New-comb received many honors and won electionto many distinguished societies. In 1874 he re-ceived the Gold Medal of the Royal AstronomicalSociety in Great Britain. He also became aFellow of the Royal Society of London in 1877and received that society’s Copley Medal in1890. The Astronomical Society of the Pacificmade him the first Bruce Gold Medallist in1898.

He died in Washington, D.C., on July 11,1909, and was buried with full military honorsat Arlington National Cemetery. To commem-orate his great contributions to the UnitedStates in the field of mathematical astronomyand nautical navigation, the navy named asurveying ship the USS Simon Newcomb.

5 Newton, Sir Isaac(1642–1727)BritishMathematician, Physicist

Only one scientist has been simultaneouslythought of in such diverse ways as “the greatestgenius that ever existed,” and “as a man, he wasa failure; as a monster he was superb.” This ge-nius monster was the famous mathematician Sir

Isaac Newton, who made perhaps the biggestcontribution of all time to the field of astron-omy with the scientific notions he devised as a22-year-old on his family’s farm.

December 25, 1642, Christmas Day, was aday to be remembered in astronomy. In Italy, thefamous mathematician and scientist GALILEO

GALILEI passed away, blind from too many ob-servations of the Sun, and under house arrest bythe Roman Catholic Church—courtesy of theInquisition for his beliefs in a heliocentric uni-verse, which he was forced to recant 10 yearsearlier to avoid being tortured to death. As onegreat life ended, another began in Woolsthorpe,England, where on this day Isaac Newton was

When the brilliant English physicist and mathematicianIsaac Newton published his great work The Principiain 1687, he single-handedly transformed the practiceof physical science and completed the scientificrevolution started by Copernicus, Galileo, and Kepler.He is considered one the greatest scientific minds thatever lived. (Original engraving by unknown artist,courtesy AIP Emilio Segrè Visual Archives, PhysicsToday Collection)

218 Newton, Sir Isaac

born—the first child of the recently widowedHannah Ayscough. Newton was named for hisfather, an illiterate but wealthy farmer who haddied three months earlier.

From age two, the young Newton was passedaround among his relatives after his mother re-married, living mostly with his grandparents.Newton hated his stepfather, Barnabus Smith,once even threatening to burn his house downwith his mother and stepfather in it. After Smithdied when Newton was 10, the boy was reunitedwith his mother and her three children by Smith,and then promptly sent away to school. His firstattempt at education was brief—he was pulledout of school after just a few months because helacked any visible ability to learn. But at age 13,after failing miserably at taking over the task ofrunning his mother’s estate, Newton was sentback to school, and this time he enjoyed learn-ing so much that he wrote it must be “a sin.”

At the very late age of 18, in 1661, Newtonentered Trinity College at Cambridge. With nofinancial backing from his mother, Newton wasobliged to work as a “sizar”—a servant to thewealthier students in exchange for financial aidto attend the university. In 1663 he got his firstlook at Euclid’s Elements, and he suddenly be-came entranced with mathematics. He graduatedin 1665, the university closed because of theplague, and Newton went back to his family’sfarm where he spent the next year and a half do-ing nothing spectacular—nothing but devisingthe laws that changed the world’s understandingof the universe.

As a 22-year-old on the farm, Newton hadtime to let his scientific mind conjure up thecreative ideas for which he is known today, in-cluding calculus, the laws of motion, and theUniversal Law of Gravity. Newton’s laws of mo-tion consist of three laws that deal with mass andforce and are the basis for Newtonian mechanics,both on Earth and in space.

The First Law of Motion is based on iner-tia, a concept Galileo introduced around a half-

century before Newton was born. It states thatan object at rest stays at rest, and an object inmotion stays in motion in a straight line and ata constant speed unless an outside influence orforce acts upon that object. More scientifically,it is written, “In the absence of outside forces,the momentum of a system remains constant.”Momentum can be simply defined as the prod-uct of mass and velocity: momentum 5 mass 3velocity.

The Second Law of Motion deals withforce, and so is about change in momentum. Itstates, “If a force acts upon a body, the body ac-celerates in the direction of the force, its mo-mentum changing at a rate numerically equalto that force.” As with the first law, if there isno force, there is no change in momentum.Acceleration is the rate at which velocitychanges, and so force is often the product of massand acceleration: force 5 mass 3 acceleration.But if the mass of a body changes—for exam-ple, if the weight of a rocket diminishes as fuelburns out of it—then the formula is not quiteso simple.

If the acceleration to a body occurs in thesame direction as the velocity of the body, thenthe object speeds up. An example of this is theforce of gravity accelerating the momentum ofa falling object, which occurs at a rate of 32feet per second2. If a force is accelerating inthe opposite direction of the momentum of abody, then it slows the object down, for ex-ample, the force of friction. Newton also ex-plained the computations for two or moreforces acting on one object; and if two forcescancel each other, then the body does not ac-celerate but instead stays in a state of equilib-rium.

Newton’s Third Law of Motion is the famous“reaction” law: “For every action, there is anequal and opposite reaction.” This was an orig-inal concept in which Newton states that allforces happen in pairs that are mutually equaland opposite to one another.

Newton, Sir Isaac 219

Newton also needed to explain the idea ofcircular momentum, because if a force on a bodycauses the object to accelerate in a straight line,how could anything travel in a circular path? Forthis to happen, there has to be a constant forceof acceleration toward the center of the circle.This is called centripetal acceleration, or cen-tripetal force. Both Newton and a Dutch physi-cist, Christiaan Huygens (1629–95), arrived atthis idea independently—Newton in 1666, whichof course he did not publish, and Huygens in1673, which he published. The equation is thatforce is equal to the product of mass and vol-ume squared, divided by the radius of the circle:F 5 mv2/r.

The Universal Law of Gravitation is thefamous “apple falling off the tree” law that chil-dren are taught when they first learn aboutgravity in school. The laws of motion, the for-mula for centripetal force, and JOHANNES

KEPLER’s laws helped Newton arrive at the Lawof Gravitation. The formula shows that theforce between two bodies is the constantof gravitation times the mass of each of thetwo bodies separated by the distance squared:F 5 G(m1m2/d2). Newton stated it as “Betweenany two objects anywhere in space there exists aforce of attraction that is in proportion to theproduct of the masses of the objects and ininverse proportion to the square of the distancebetween them.”

Newton’s laws are generally acceptable formost, but not all, natural physics. The twoexceptions are relativity, explained by ALBERT

EINSTEIN, and quantum theory, which Newtonianmechanics cannot describe.

In order to give all of the necessary compu-tations for his laws, Newton created calculusduring his stay on the farm. Then, in 1667, hereturned to Cambridge to work on his master’sdegree, and two years later became LucasianProfessor in mathematics, a position that wouldalso be held 300 years later by SIR STEPHEN

WILLIAM HAWKING. Newton made little mention

of his calculus or any other work when he re-turned to Cambridge.

Instead, Newton was interested in optics,and he soon discovered that white light is madeof a spectrum of colors—red, orange, yellow,green, blue, indigo, and violet—and can be seenwhen a ray of light is bent, or refracted, for ex-ample through a glass prism. This discovery con-cerned Newton about the optics of refractingtelescopes, so he invented a reflecting telescope.Then, in 1672, he gave one of his new telescopesto the Royal Society. In honor of his gift, he waselected as a member to the society and was al-lowed to publish his first paper on optics and theproperties of light.

Trouble soon followed. Mathematician RobertHooke had discussed his ideas on light withNewton, and when Hooke saw these conceptsin print he accused Newton of stealing his work.Huygens didn’t agree with Newton’s science.And the Jesuits saw his ideas as an attack onChristianity and sent him a barrage of violentletters. After years of badgering, Newton couldno longer stand the pressure, and in 1678 hesuffered his first nervous breakdown.

After such disastrous results with publishing,it is surprising that any of Newton’s later workever made it into print. But the famous as-tronomer SIR EDMUND HALLEY, who soughtNewton’s help to work on the problem of orbits,discovered that Newton had developed the lawsof motion and gravity and had the calculus toback it up. He pushed Newton to publish hiswork, and Newton agreed only after Halley of-fered to pay for the printing with his ownmoney. In 1687 the first edition of 2,500 copiesof Philosophiae Naturalis Principia Mathematica(Mathematical principles of natural philosophy)was published, and Principia, as it becameknown, put Newton in the ranks of the greatestscientific minds ever to grace the planet.

But Newton was busy with the politics ofthe university and the state, publicly fightingKing James II’s decree to fill the university’s

220 Newton, Sir Isaac

teaching positions with academically unquali-fied Catholics. When William of Orange oustedJames II, Newton was rewarded for his stancewith a seat in Parliament. From 1689 to 1693Newton filled his time with both the universitywork and his new work in government, butagain the pressures of life took hold of him, andhe suffered another nervous breakdown. It tookseveral years for him to get back on his feet, butwhen he did, in 1696, he became extremelywealthy as the head of the Royal Mint.

The Royal Society elected Newton as pres-ident in 1703, and in 1704, after Hooke’s death,he published his entire work on optics, part ofwhich had caused the scandal with Hooke ear-lier in his career. For Newton’s now famous workin science, Queen Anne knighted him in 1705,giving him the honor of being the first man everknighted for scientific achievement.

In 1711 controversy struck again, this timein a disastrous scandal involving the famous math-ematician Gottfried Wilhelm Leibniz (1646–1716),who was commonly regarded as the inventorof calculus. An article published by the RoyalSociety, of which Newton was then president, ac-cused Leibniz of plagiarism and declared Newtonas the inventor of calculus. Newton was knownfor being a horrid man, and in a position of powerhe could do whatever he wanted to guarantee thatthings went his way. He announced that he wasappointing an “impartial committee” to deter-mine who really invented calculus, then wrote ananonymous decision on behalf of the RoyalSociety in favor of himself, and promptly closedthe case, officially pronouncing himself the true

inventor. Leibniz was never allowed to give anyevidence in his defense, and the issue became ahotly debated international incident.

Newton died in 1727, and two years later, 42years after its original publication, Principia wastranslated from its original Latin into English.Newton was buried in Westminster Abbey, witha Latin inscription on his tomb that reads,“Mortals! Rejoice at so great an ornament to thehuman race.” The Leibniz incident followedboth Newton and Leibniz all the way to theirgraves, and remained an international debateyears after their deaths (Leibniz and Newton arenow considered to have independently inventedcalculus).

The French mathematician COMTE JOSEPH-LOUIS LAGRANGE called Newton “the greatestgenius that ever existed,” and SUBRAHMANYAN

CHANDRASEKHAR considered his brilliance sec-ond to none, not even Einstein. But in Newton’scase, scientific brilliance had its “equal and op-posite” dark side in a mean-spirited and evil tem-perament. Newton ordered several counterfeit-ers executed by the state, and he had nastypublic fights with other important figures, notthe least of whom was the Astronomer RoyalJohn Flamsteed. Newton was superbly mon-strous, an observation written by the literaryphilosopher Aldous Huxley (1894–1963) and aview shared by many, both during and afterNewton’s lifetime. Yet his professional contribu-tions to astronomy were nothing short of genius.To his credit, Newton has said, “If I have seenfarther than others, it is because I was standingon the shoulders of giants.”

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O5 Oberth, Hermann Julius

(1894–1989)Romanian/GermanMathematician, Physicist, (Theoretical)Rocket Engineer

The Transylvanian-born German physicist Her-mann Oberth was a theoretician who helpedestablish the field of astronautics early in the 20thcentury. He originally worked independently ofKONSTANTIN EDUARDOVICH TSIOLKOVSKY andROBERT HUTCHINGS GODDARD in his advocacy ofrockets for space travel, but later discovered andacknowledged their prior efforts. Unlike Tsi-olkovsky and Goddard, however, Oberth madehuman beings an integral part of the spacetravel vision. His inspirational 1923 publicationThe Rocket into Interplanetary Space provided acomprehensive discussion of all the majoraspects of space travel, and his 1929 award-win-ning book, Roads to Space Travel, popularizedthe concept of space travel for technical andnontechnical readers alike. His technical publi-cations and inspiring lectures exerted a tremen-dous career influence on many young Germans,including the legendary WERNHER MAGNUS

VON BRAUN.Oberth was born on June 25, 1894, in the

town of Hermannstadt in a German enclavewithin the Transylvanian region of Romania

(part of the Austro-Hungarian Empire). His par-ents were members of the historically German-speaking community of the region. His father,Julius, was a prominent physician who tried toinfluence his son in a career in medicine. ButHermann was a free-spirited thinker who pre-ferred to ponder the future while challengingthe ideas held by the current scientific estab-lishment.

At age 11 Oberth discovered the works ofJules Verne, especially De la terre à la lune (Fromthe Earth to the Moon). In his famous 1865novel, Verne was first to provide young readerslike Oberth a somewhat credible account of ahuman voyage to the Moon. Verne’s travelers areblasted on a journey around the Moon in a spe-cial hollowed-out capsule fired from a large can-non. Verne correctly located the cannon at alow-latitude site on the west coast of Floridacalled “Tampa Town.” By coincidence, this fic-titious site is about 120 kilometers to west ofLaunch Complex 39 at the NASA KennedySpace Center from which Apollo astronauts ac-tually left for journeys to the Moon between1968 and 1972.

Oberth read this novel many times andthen, while remaining excited about spacetravel, questioned the story’s technical plausi-bility. He soon discovered that the accelerationdown the barrel of this huge cannon would have

222 Oberth, Hermann Julius

Hermann Oberth, one of the founding fathers of astronautics, appears in the forefront of this 1956 photograph,accompanied by officials of the U.S. Army Ballistic Missile Agency at Huntsville, Alabama. Included behind Oberth(from left to right) are Ernst Stuhlinger (seated), Major General H. N. Toftoy (uniformed, standing), Wernher vonBraun (seated on table), and Eberhard Rees (standing, far right). General Toftoy was the American military officerresponsible for “Project Paperclip”—the operation that took rocket scientists and engineers (including Oberth, vonBraun, and Stuhlinger) out of Germany after World War II and relocated them in the United States so they couldhelp design U.S. rockets during the cold war. (Courtesy of NASA)

Oberth, Hermann Julius 223

crushed the intrepid explorers and that the cap-sule itself would have burned up in Earth’s at-mosphere. But Verne’s story made space travelappear technically possible, and this importantidea thoroughly intrigued Oberth. So, after iden-tifying the technical limitations in Verne’s fic-tional approach, he started searching for a morepractical way to travel into space. That searchquickly led him to the rocket.

In 1909, at age 15, Oberth completed hisfirst plan for a rocket to carry several people. Hisdesign for a liquid-propellant rocket that burnedhydrogen and oxygen came three years later. Hegraduated from the Gymnasium (high school) inJune 1912, receiving an award in mathematics.The next year he entered the University ofMunich with the intention of studying medi-cine, but World War I interrupted his studies.As a soldier, he was wounded and transferred toa military medical unit. To the great disap-pointment of his father, Oberth’s three years ofduty in this medical unit reinforced his decisionnot to study medicine.

During World War I Oberth tried to inter-est the Imperial German War Ministry in de-veloping a long-range military rocket. In 1917he submitted his specific proposal for a largeliquid-fueled rocket. He received a very abruptresponse for his efforts. Certain Prussian arma-ments “experts” within the ministry quicklyrejected his plan and reminded him that theirexperience clearly showed that military rocketscould not fly farther than seven kilometers. Ofcourse, these officials were limited by their ownexperience with contemporary military rocketsthat used inefficient black powder for propellant.They totally missed Oberth’s breakthroughidea involving a better-performing liquid-fueledrocket.

Undaunted, Oberth returned to the univer-sity and continued to investigate the theoreticalproblems of rocketry. In 1918 he marriedMathilde Hummel and a year later went back tothe University of Munich to study physics. He

studied at the University of Göttingen then atthe University of Heidelberg before becomingcertified as a secondary-school mathematics andphysics teacher in 1923. At this point in his life,he was unaware of the contemporary rocket the-ory work by Tsiolkovsky in Russia and Goddardin the United States. In 1922 he presented adoctoral dissertation on rocketry to the facultyat the University of Heidelberg, but the univer-sity committee rejected his dissertation.

Still inspired by space travel, he revised thiswork and published it in 1923 as Die Rakete zuden Planetenräumen (The rocket into interplane-tary space). This modest book provided a thor-ough discussion of the major aspects of spacetravel, and its contents inspired many youngGerman scientists and engineers to explore rock-etry, including WERNHER MAGNUS VON BRAUN.Oberth worked as a teacher and writer in the1920s. He discovered and acknowledged therocketry work of Goddard and Tsiolkovsky inthe mid-1920s and became the organizing figurearound which the practical application of rock-etry developed in Germany. He served as a lead-ing member of Verein für Raumschiffahrt (VFR),the German Society for Space Travel. Membersof this technical society conducted critical ex-periments in rocketry in the late 1920s andearly 1930s, until the German army absorbedtheir efforts and established a large militaryrocket program.

Fritz Lang (1890–1976), the popular Austrianfilmmaker, hired Oberth as a technical adviserduring the production of his 1929 film DieFrau im Mond (The woman in the moon).Collaborating with Willy Ley (1906–69), Oberthprovided for the film an exceptionally prophetictwo-stage cinematic rocket that startled and de-lighted audiences with its impressive blastoff.Lang, ever the showman, also wanted Oberthto build and launch a real rocket as part of apublicity stunt to promote the new film.Unfortunately, with little engineering experi-ence, Oberth accepted Lang’s challenge, but

224 Olbers, Heinrich Wilhelm Matthäus

was soon overwhelmed by the arduous task ofturning theory into practical hardware. Shockedand injured by a nearly fatal liquid-propellantexplosion, Oberth abandoned Lang’s publicityrocket and retreated to the comfort and safetyof writing and teaching mathematics in hisnative Romania.

Oberth was a much better theorist and tech-nical writer than nuts-and-bolts rocket engineer.In 1929 Oberth expanded his ideas concerningthe rocket for space travel and human space flightin a book entitled Wege zur Raumschiffahrt (Roadsto space travel). The Astronomical Society ofFrance gave Oberth an award for this book,which helped popularize the concept of spacetravel for both technical and nontechnical audi-ences. As newly elected president of the VFR,Oberth used some of his book’s prize money tofund rocket engine research within the society.Young engineers like Braun had a chance to ex-periment with liquid-propellant engines, includ-ing one of Oberth’s concepts, the Kegeldüse(conic) engine design. In this visionary book,Oberth also anticipated the development ofelectric rockets and ion propulsion systems.

Throughout the 1930s, Oberth continued towork on liquid-propellant rocket concepts and onthe idea of human space flight. In 1938 Oberthjoined the faulty at the Technical University ofVienna. There, he participated briefly in a rocket-related project for the German air force. In 1940he became a German citizen. The following year,he joined Braun’s rocket development team atPeenemünde.

Oberth worked only briefly with Braun. In1943 he transferred to another location to workon solid-propellant antiaircraft rockets. At theend of World War II, Allied forces captured himand placed him in an internment camp. Uponrelease, he left a devastated Germany and soughtrocket-related employment as a writer and lec-turer in Switzerland and Italy. In 1955 he joinedBraun’s team again, this time at the U.S. Army’sRedstone Arsenal. He worked there for several

years before returning to Germany in 1958 andretiring.

Of the three founding fathers of astronau-tics, only Oberth lived to see some of hispioneering visions come true. These visions in-cluded the dawn of the Space Age (1957, withSputnik 1), human space flight (1961), the firsthuman landing on the Moon (1969), the firstspace station (1971), and the first flight of areusable launch vehicle—NASA’s Space Shuttle(1982). He died in Nuremberg, Germany, onDecember 29, 1989. Oberth studied the theo-retical problems of rocketry and outlined thetechnology needed for people to live and workin space. The last paragraph of his 1954 book,Man into Space, addresses the important ques-tion: “Why space travel?” His eloquently philo-sophical response is, “This is the goal: To makeavailable for life every place where life is possi-ble. To make inhabitable all worlds as yet unin-habitable, and all life purposeful.”

5 Olbers, Heinrich Wilhelm Matthäus(1758–1840)GermanAstronomer (Amateur)

Sometimes a person is primarily remembered forasking an interesting question that baffles thebest scientific minds of the time. The Germanastronomer Heinrich Wilhelm Matthäus Olberswas just such a person. To his credit as an ob-servational astronomer, he discovered the main-belt asteroids Pallas in 1802 and Vesta in 1807.Today he is best remembered for formulating theinteresting philosophical question now knownas Olber’s paradox. In about 1826 he challengedhis fellow astronomers by posing the followingseemingly innocent question: “Why isn’t thenight sky with its infinite number of stars not asbright as the surface of the Sun?”

Olbers was born on October 11, 1758, atArdbergen (near Bremen), Germany. The son of

Olbers, Heinrich Wilhelm Matthäus 225

a Lutheran minister, he entered the Universityof Göttingen in 1777 to study medicine, but alsotook courses in mathematics and astronomy. By1781 he became qualified to practice medicineand established a practice in Bremen. By day, heserved his community as a competent physician;in the evening he pursued his hobby of astron-omy. He converted the upper floor of his homeinto an astronomical observatory and used sev-eral telescopes to conduct regular observations.

“Comet hunting,” or cometography, was afavorite pursuit of 18th-century astronomers,and Olbers, a dedicated amateur astronomer,eagerly engaged in this quest. In 1796 he dis-covered a comet and then used a new mathe-matical technique he had developed to computeits orbit. His technique, often referred to asOlber’s method, proved computationally efficientand was soon adopted by many other astronomers.At the start of the 19th century, Olbers contin-ued to successfully practice medicine in Bremen,but he also became widely recognized as a skilledastronomer.

At the end of the 18th century, astronomersbegan turning their attention to the interestinggap between Mars and Jupiter. At the time, pop-ularization of the Titius-Bode law—actually justan empirical statement of relative planetary dis-tances from the Sun—caused astronomers tospeculate that a planet should have been in thisgap. Responding to this wave of interest,GIUSEPPE PIAZZI discovered the first and largestof the minor planets, which he named Ceres, onthe first of January in 1801. Unfortunately, Piazzisoon lost track of Ceres. However, based onPiazzi’s few observations, the brilliant Germanmathematician Carl Friedrich Gauss (1777–1855) was able to calculate its orbit. Consequently,a year later, on January 1, 1802, Olbers relocatedCeres. While observing Ceres, Olbers also dis-covered another minor planet, Pallas. He contin-ued looking in the gap and found the thirdmain-belt asteroid, Vesta, in 1807. Anticipatingthe discovery of solar radiation pressure, he

suggested in 1811 that a comet’s tail points awayfrom the Sun during perihelion passage becausethe material ejected by the comet’s nucleus is in-fluenced (pushed) by the Sun. He remained anactive observational astronomer and discoveredfour more comets, including one in 1815 thatnow bears his name.

Olbers is best remembered, however, forpopularizing the question “Why is the night skydark?” He presented a technical paper in 1826that attempted to solve this interesting puzzle.Previous astronomers in the 17th and 18th cen-tury were certainly aware of this question, whichis sometimes traced back to the writings of the17th-century astronomer JOHANNES KEPLER, orto a 1744 publication by the Swiss astronomerJean-Philippe Loys de Chéseaux. However,Olbers’s paper represents the most enduring for-mulation of the question, which is now knownas Olber’s paradox.

Within the perspective of 19th-century cos-mology, the basic problem can be summarized asfollows: If the universe is infinite, unchanging,homogeneous, and therefore filled with stars (inthe early 20th century “galaxies” was included),then the entire night sky should be filled withlight and as bright as daytime. Of course, Olberssaw that night sky was obviously not bright asthe day—so what accounted for this inconsis-tency or paradox between observation and the-ory? Olbers explanation suggested that the dustand gas in interstellar space blocked much of thelight traveling to Earth from distant stars.Unfortunately, he was wrong in this particularsuggestion, because within his cosmologicalmodel, such absorbing gas would have heated upto incandescent temperatures and glowed.

To solve this apparent contraction, Olbersneeded to discard the prevalent infinite, static,homogeneous model of the universe and dis-cover Big Bang cosmology, with its expanding,finite, and inhomogeneous universe. Modern as-tronomers now provide a reasonable explanationof Olber’s paradox with the assistance of an

226 Oort, Jan Hendrik

expanding, finite universe model. Some suggestthat as the universe expands the very distantstars and galaxies become obscure due to exten-sive redshift—a phenomenon that weakens theirapparent light and makes the night sky dark.Other astrophysicists declare that the observedredshift to lower energies is not a sufficient rea-son to darken the sky. They suggest that the fi-nite extent of the physical, observable universeand its changing time-dependent nature providethe reason the night sky is truly dark—despitethe faint amounts of starlight reaching Earth.

Today, modern cosmology explains that theuniverse is dynamic and not statically filled upwith unchanging stars and galaxies. Finally, asinherently implied within Big Bang cosmology,since the universe is finite in extent and thespeed of light is assumed constant, there has noteven been a sufficient amount of time for thelight from those galaxies beyond a certain range(called the observable universe) to reach Earth.

Olbers died in Bremen, Germany, on March2, 1840. The chief astronomical legacy of thissuccessful German physician and accomplishedamateur astronomer is Olber’s paradox—a co-herent response to which helps scientists high-light some of the most important aspects and im-plications of modern cosmology.

5 Oort, Jan Hendrik(1900–1992)DutchAstronomer

An accomplished astronomer, Jan Oort madepioneering studies of the dimensions and struc-ture of the Milky Way Galaxy in the 1920s.However, he is now most frequently rememberedfor the interesting hypothesis he extended in1950 when he postulated that a large swarm ofcomets circles the Sun at a great distance—somewhere between 50,000 and 100,000 astro-nomical units. Today astronomers refer to this

very distant, postulated reservoir of icy bodies asthe Oort cloud in his honor.

Oort was born in the township of Franeker,in Friesland Province, the Netherlands, on April28, 1900. At age 17 he entered the Universityof Groningen where he studied stellar dynamicsunder JACOBUS CORNELIUS KAPTEYN. He com-pleted his doctoral coursework in 1921 and re-mained at the university as a research assistantfor Kapteyn for about one year. He thenperformed astrometry-related research at YaleUniversity between 1922 and 1924. Upon re-turning to Holland in 1924, he accepted an

The Dutch astronomer Jan Oort, shown here at hisdesk in 1986, made pioneering studies of thedimensions and structure of the Milky Way Galaxy inthe 1920s. He also boldly speculated in 1950 that alarge swarm of comets (now called the Oort cloud)encircles the Sun at a great distance—somewherebetween 50,000 and 100,000 astronomical units.(Photo by Ron Doel, courtesy AIP Emilio Segrè VisualArchives)

Oort, Jan Hendrik 227

appointment as a staff member at LeidenObservatory and remained affiliated with theUniversity of Leiden in some capacity for theremainder of his life.

Following completion of all the require-ments for his doctoral degree in 1926, Oortbegan making important contributions to our un-derstanding of the structure of the cosmos. Duringseven decades of productive intellectual activity,Oort made significant contributions to the rap-idly emerging body of astronomical knowledge.At the start of his career, the universe was con-sidered to be contained within just the Milky WayGalaxy—a vast collection of billions of starsbound within some rather poorly defined borders.When he published his last paper in 1992, Oortwas busy describing some of the interesting char-acteristics of an expanding universe now con-sidered comprised of billions of galaxies whosespace and time dimensions extending in all di-rections to the limits of observation.

In 1927 he revisited Kapteyn’s star stream-ing data, while also building upon the recentwork of the Swedish astronomer Bertil Lindblad(1895–1965). This approach produced a classicpaper in which Oort demonstrated that thedifferential systematic motions of stars in thesolar neighborhood could be explained in termsof a rotating galaxy hypothesis. The paper,“Observational Evidence Confirming Lindblad’sHypothesis of a Rotation of the GalacticSystem,” served as Oort’s platform for introduc-ing his concept of differential galactic rotation.

Differential rotation occurs when differentparts of a gravitationally bound gaseous systemrotate at different speeds. This implies that thevarious components of a rotating galaxy share inthe overall rotation around the common centerto varying degrees. Oort continued to pursue ev-idence for differential galactic rotation and wasable to establish the mathematical theory ofgalactic structure.

Starting in 1935, Oort served the Universityof Leiden as both an associate professor of as-

tronomy and a joint director of the observatory.In 1945, at the end of World War II, he receiveda promotion to full professor and the position ofthe director of its observatory. He continued hisuniversity duties until retirement in 1970.However, after retirement from the university, hestill continued to work regularly at the LeidenObservatory and produced technical papers un-til just before his death on November 5, 1992.

Despite the research-limited conditions thatcharacterized German-occupied Holland duringWorld War II, Oort saw the important galacticresearch potential of the newly emerging fieldof radio astronomy. He therefore strongly en-couraged his graduate student Hendrik van deHulst (1918–2000) to investigate whether hy-drogen clouds might emit a useful radio fre-quency signal. In 1944 van de Hulst was ableto theoretically predict that hydrogen shouldhave a characteristic radio wave emission at awavelength of 21 centimeters.

After Holland recovered from World War IIand the University of Leiden returned to its nor-mal academic functions, Oort was able to forma Dutch team, including van de Hulst, whichdiscovered in 1951 the predicted 21-centimeterwavelength radio frequency emission from neu-tral hydrogen in outer space. By measuring thedistribution of this telltale radiation, Oort andhis colleagues mapped the location of hydrogengas clouds throughout the Galaxy. Then, theyused this application of radio astronomy to findthe large-scale spiral structure of the Galaxy, thelocation of the galactic center, and the charac-teristic motions of large interstellar clouds ofhydrogen.

Throughout his career as an astronomer,comets remained one of Oort’s favorite topics.Oort supervised completion of research by apostwar doctoral student who was investigatingthe origin of comets and the statistical distri-bution of the major axes of their elliptical or-bits. Going beyond this student’s research, Oortdecided to investigate the consequences that

228 Oort, Jan Hendrik

passing rogue stars might have on cometaryorbits.

As early as 1932, the Estonian astronomerErnst Öpik (1893–1985) had suggested that thelong-period comets that occasionally dashedthrough the inner solar system might reside insome gravitationally bound cloud at a great dis-tance from the Sun. In 1950 Oort revived andextended the concept of a heliocentric reservoirof icy bodies in orbit around the Sun. This reser-voir is now called the Oort cloud.

In refining his comet reservoir model, Oortfirst suggested that in the early solar system theseicy bodies formed at a distance of less than 30astronomical units from the Sun—that is, withinthe orbit of Neptune. But then, they diffusedoutward as a result of gravitational interactionwith the giant gaseous planets Jupiter andSaturn. According to Oort’s hypothesis, these

deflected comets then collected in a swarm orcloud that extended in distance from the Sun ofbetween 30,000 and 100,000 astronomical units.At this extreme range of distances (from about20 to 30 percent of the way to the nearest star,Proxima Centuri) the perturbations withinother stars and gas clouds helped shape the he-liocentric orbits so that only an occasionalcomet now pops out of the cloud on a visit backthrough the inner solar system. Oort’s theory hasbecome a generally accepted model for the originof very long-period comets.

He received numerous awards for his theoryof galactic structure, including the Bruce Medalof the Astronomical Society of the Pacific in1942 and the Gold Medal of the RoyalAstronomical Society in 1946. However, it is theOort cloud—his comet cloud hypothesis—thatgives his work a permanent legacy in astronomy.

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P5 Penzias, Arno Allen

(1933– )German/AmericanPhysicist, Radio Astronomer

Sometimes the world’s greatest scientific discov-eries take place when least expected. While col-laborating in the mid–1960s with ROBERT

WOODROW WILSON, a fellow radio astronomer atBell Laboratories, Arno Penzias went about thetask of examining natural sources of extraterres-trial radio wave noise that might interfere withtransmissions from communication satellites. Tohis great surprise, he and Wilson quite by acci-dent stumbled upon the “Holy Grail” of moderncosmology—the cosmic microwave background.This all-pervading microwave background radia-tion resides at the very edge of the observableuniverse and is considered the cooled remnant(about three kelvins) of the ancient big bangexplosion. They carefully confirmed the datathat rocked the world of physics and gave cos-mologists the first empirical evidence pointing toa very hot, explosive phase at the beginning ofthe universe. Penzias and Wilson shared the 1978Nobel Prize in physics for this most importantdiscovery.

Penzias was born in Munich, Germany, onApril 26, 1933. Of Jewish heritage, his family wasone of the last to successfully flee Nazi Germany

before the outbreak of World War II and escapedalmost certain death in one of Hitler’s concentra-tion camps. In 1939 his parents placed Arno andhis younger brother on a special refugee train toGreat Britain and then traveled there under sep-arate exit visas to join their sons. Once reunited,the family sailed for the United States in Decem-ber and arrived in New York City in January1940. Penzias followed the education routetaken by many thousands of upwardly mobileimmigrants. He used hard work and the NewYork City public school system as his pathway toa better life. In 1954 he graduated from the CityCollege of New York (CCNY) with a bachelor ofscience degree in physics. After graduation hemarried, then joined the U.S. Army, where heserved in the Signal Corps for two years. Hethen enrolled at Columbia University in 1956and graduated from that institution with a mas-ter of arts degree in 1958 and a Ph.D. degree in1962.

His technical experience in the army’s Sig-nal Corps allowed him to obtain a researchassistantship in the Columbia Radiation Labo-ratory. There he met and studied under CharlesTownes (b. 1915), the American physicist andNobel laureate who developed the first opera-tional maser (microwave amplification by stim-ulated emission of radiation)—the forerunnerto the laser. For a doctoral research project,

230 Penzias, Arno Allen

Professor Townes assigned Penzias the challeng-ing task of building a maser amplifier suitablefor use in a radio astronomy experiment of hisown choosing.

Upon completion of his thesis work in 1961,Penzias sought temporary employment at BellLaboratories in Holmdel, New Jersey. To his

surprise, the director of the Radio ResearchLaboratory offered him a permanent position.Penzias quickly accepted the radio astronomerposition and subsequently remained a memberof Bell Laboratories in various technical andmanagement capacities until his retirement inMay 1998.

Shown here in front of their historic radio telescope at the Bell Laboratories in New Jersey are the Noble laureates Robert Woodrow Wilson (left, background) and Arno Penzias (right, foreground). In the mid-1960s,while performing other experiments with this facility, the two radio astronomers serendipitously detected thecosmic microwave background—the cooled remnant of the “big bang” at the edge of the observable universe.Their discovery provided cosmologists the first direct evidence of a very hot, explosive phase at the beginning ofthe universe. For this great achievement, they shared the 1978 Nobel Prize in physics. (Lucent Technologies’ BellLaboratories, courtesy AIP Emilio Segrè Visual Archives, Physics Today Collection)

Penzias, Arno Allen 231

In 1963 Penzias met another radio astro-nomer, Wilson, who had recently been hired towork at Bell Laboratories after graduating fromthe California Institute of Technology (Cal-tech). The two scientists embarked on the taskof using a special horn-reflector antenna 20 feetin diameter that had just been constructed atBell Laboratories to serve as an ultra-low-noisereceiver for signals bounced from NASA’s EchoOne satellite—the world’s first passive com-munications satellite experiment, launched inAugust 1960. At the time, this ultrasensitive six-meter horn-reflector was no longer needed forsatellite work, so both Penzias and Wilson beganto modify the instrument for radio astronomy.As modified with traveling-wave maser ampli-fiers, their modest-sized horn reflector becamethe most sensitive radio telescope in the world atthe time. Both radio astronomers were eager toextend portions of their doctoral research withthis newly converted radio telescope. Their ini-tial objective was to measure the intensity ofseveral interesting extraterrestrial radio sourcesat a radio frequency wavelength of 7.53 cen-timeters—a task with potential value in boththe development of satellite-based telecommu-nications and radio astronomy.

On May 20, 1964, Wilson and Penzias madea historic measurement that later proved to bethe very first to clearly indicated the presence ofthe cosmic microwave background—the remnant“cold light” from the dawn of creation. At thetime, neither was sure why this strange back-ground “noise” at around three degrees Kelvinequivalent temperature kept showing up in allthe measurements. As excellent scientists do,they checked every potential source for thisunexplained signal. They ruled out equipmenterror (including antenna noise due to faultyjoints), the lingering effects of a previous nucleartest in outer space, the presence of human-maderadio frequency signals (including those ema-nating from New York City), sources withinthe Milky Way Galaxy, and even the possible

echoing effects of pigeon droppings from a pairof birds that made a portion of the antennatheir home. Nothing explained this persistent,omnidirectional, uniform microwave signal. Byearly 1965 Penzias and Wilson had completedtheir initial data collection with their antenna,but were still no closer to unraveling the truephysical nature of this persistent signal. Theircareful analysis indicated the signal was definitely“real”—but what was it?

Then the mystery unraveled quickly when,during a meeting with another physicist in spring1965, Penzias casually mentioned his recentradio astronomy work and the interesting noise-like signal he and Wilson had collected. Thephysicist suggested that Penzias contact RobertDicke (1916–97) and members of his group atPrinceton University who were exploring thephysics of the universe and something calledthe big bang hypothesis. Penzias contactedDicke who soon visited Bell Laboratories. Afterhe reviewed their precise work, Dicke immedi-ately realized that Penzias and Wilson had, totallyby accident, beaten all the other astrophysicistsand cosmologists, including Dicke, in detectingevidence of the hypothesized microwave remnantof the big bang. Recognizing the scientific impor-tance of this work, they agreed to publish lettersin the Astrophysical Journal. As a result, Volume142 of the Astrophysical Journal contains two his-toric letters that appear side by side. In one letter,Dicke and his team at Princeton University dis-cuss the cosmological implications of the cosmicmicrowave background; in the other letter, Pen-zias and Wilson present their cosmic microwavebackground measurements without elaboratingon the cosmological significance of the data.

Once the Penzias and Wilson data began tocirculate within the astronomical community, itstrue significance quickly emerged. Scientists re-visited the earlier big bang hypothesis work ofRALPH ASHER ALPHER and engaged in a series ofcorroborating measurements. For providing thefirst definitive evidence of the cosmic microwave

232 Piazzi, Giuseppe

background, Penzias and Wilson shared the1978 Nobel Prize in physics with the Russianphysicist Pyotr Kapitsa, who received his awardfor unrelated achievements in low-temperaturephysics.

While responding to the research needs andpriorities of Bell Laboratories in the 1960s and1970s, Penzias and Wilson also continued to par-ticipate in pioneering radio astronomy research.In 1973, while investigating molecules in inter-stellar space, they discovered the presence of thedeuterated molecular species DCN and werethen able to use this molecular species to tracethe distribution of deuterium in the Galaxy. In1972 Penzias became head of the Radio PhysicsResearch Department at Bell Laboratories, andearly in 1979 his management responsibilitiesincreased when he received a promotion tohead the laboratory’s Communications SciencesResearch Division. At the end of 1981, he re-ceived another promotion and became vice pres-ident of research as the Bell System experienceda major transformation. While discharging hisresponsibilities in this new executive position,Penzias began to concentrate on the creationand effective use of new technologies. In 1989he published a book, Ideas and Information,which discussed the impact of computers andother new technologies on society. In May 1998Penzias retired from his position as chief scientistat Bell Laboratories, now a division of LucentTechnologies.

Best known as the radio astronomer whocodiscovered the cosmic microwave background,Penzias received many awards and honors in ad-dition to his 1978 Nobel Prize. Some of his otherawards include the Henry Draper Medal of theAmerican National Academy of Sciences (1977)and the Herschel Medal of the Royal AstronomicalSociety (1977). He also received membership inmany distinguished organizations, including theNational Academy of Sciences, the AmericanAcademy of Arts and Sciences, and the AmericanPhysical Society.

5 Piazzi, Giuseppe(1746–1826)ItalianAstronomer

In the late 18th century this intellectually giftedItalian monk was a professor of mathematics atthe academy in Palermo and also served as thedirector of the new astronomical observatoryconstructed in Sicily in 1787. Piazzi was a skilledobservational astronomer and discovered thefirst asteroid on New Year’s Day in 1801. Fol-lowing prevailing astronomical traditions, henamed the newly found celestial object Ceres,after the patron goddess of agriculture in Romanmythology.

Giuseppe Piazzi was born at Ponte, in Val-tellina, Italy, on July 16, 1746. Early in his lifehe decided to enter the Theatine Order, a reli-gious order for men founded in southern Italy inthe 16th century. Upon completing his initialreligious training, Piazzi accepted the order’sstrict vow of poverty. As a newly ordainedmonk, he pursued advanced studies at collegesin Milan, Turin, Genoa, and Rome. Piazziemerged as a professor of theology and a profes-sor of mathematics. In the late 1770s he taughtbriefly at the university on the island of Maltaand then returned to a college post in Rome toserve with distinction as a professor of dogmatictheology. His academic colleague in Rome wasanother monk named Luigi Chiaramonti, whowas later elected Pope Pius VII (1800–23). In1780 his religious order sent Piazzi to the acad-emy in Palermo to assume the chair of highermathematics.

While working at this academy in Sicily,Piazzi obtained a grant from the viceroy of Sicily,Prince Caramanico, to construct an observatory.As part of the development of this new obser-vatory, he traveled to Paris in 1787 to study as-tronomy with Joseph Lalande (1732–1807) andthen went on to Great Britain the following yearto work with England’s fifth Astronomer Royal,

Pickering, Edward Charles 233

Nevil Maslelyne (1732–1811). As a result of histravels, Piazzi gathered new astronomical equip-ment for the observatory in Palermo. Upon re-turning to Sicily, he set up the new equipmenton top of a tower in the royal palace between1789 and 1790.

All was soon ready and Piazzi began to makeastronomical observations in May 1791. Hepublished his first astronomical reports in 1792.His primary goal was to improve the stellar po-sition data in existing star catalogs. Piazzi paidparticular attention to compensating for errorsinduced by such subtle phenomenon as theaberration of starlight, discovered in 1728 bythe British astronomer JAMES BRADLEY. Themonk-astronomer was a very skilled observerwho was soon able to publish a refined positionallist of approximately 6,800 stars in 1803. He fol-lowed this initial effort with the publication ofa second star catalog containing about 7,600stars in 1814. Both of these publications werewell received within the astronomical commu-nity and honored by prizes from the Frenchacademy.

However, Piazzi is today best remembered asthe person who discovered the first asteroid (orminor planet). He made this important discov-ery on January 1, 1801, from the observatorythat he founded and directed in Palermo. Toplease his royal benefactors while still maintain-ing astronomical traditions, he called the newcelestial object Ceres, after the ancient Romangoddess of agriculture who was once widely wor-shiped on the island of Sicily. Ceres (asteroid 1)is the largest asteroid, with a diameter of about935 kilometers. However, because of its very lowalbedo (about 10 percent), Ceres cannot beobserved by the naked eye. After just three goodtelescopic observations in early 1801, Piazzi lostthe asteroid in the Sun’s glare. Yet Piazzi’s care-fully recorded positions enabled the brilliantGerman mathematician Carl Friedrich Gauss(1777–1855), to accurately predict the asteroid’sorbit. Gauss’s calculations allowed another early

asteroid hunter, HEINRICH WILHELM MATTHÄUS

OLBERS, to relocate the minor planet on January1, 1802. Olbers then went on to find the aster-oids Pallas (1802) and Vesta (1807).

When Piazzi died in Naples, Italy, on July22, 1826, only four asteroids were known to ex-ist in the gap between Mars and Jupiter. But ishis pioneering discovery of Ceres in 1801 stim-ulated renewed attention on this interestingregion of the solar system—a gap that shouldcontain a missing planet according to the Titus-Bode law. In 1923 astronomers named the 1,000thasteroid discovered “Piazzia” to honor the Italianastronomer’s important achievement.

5 Pickering, Edward Charles(1846–1919)AmericanAstronomer, Physicist

Starting in 1877, Edward Charles Pickering dom-inated American astronomy for the last quarterof the 19th century. He served as the director ofthe Harvard College Observatory for more thanfour decades, and in this capacity supervised theproduction of the Henry Draper Catalogue byANNIE JUMP CANNON, WILLIAMINA PATON

STEVENS FLEMING, HENRIETTA SWAN LEAVITT,and other astronomical “computers.” This impor-tant work listed more than 225,000 stars accord-ing to their spectra, as defined by the newlyintroduced Harvard Classification System. Healso vigorously promoted the exciting new fieldof astrophotography, and in 1889 discovered thefirst spectroscopic binary star system—two starsso visually close together that they can bedistinguished only by the Doppler shift of theirspectral lines.

Pickering was born on July 19, 1846, inBoston, Massachusetts. After graduating fromHarvard University in 1865, he taught physicsfor approximately 10 years at the MassachusettsInstitute of Technology (MIT). To assist in his

234 Pickering, Edward Charles

physics lectures, he constructed the first instruc-tional physics laboratory in the United States.Then, in 1876, at just 30 years of age, he becamea professor of astronomy and the director of theHarvard College Observatory. He remained inthis position for 42 years and used it to effectivelyshape the course of American astronomy throughthe last two decades of the 19th century and thefirst two decades of the 20th century.

One important innovation was Pickering’sdecision to hire women to work as observationalastronomers and “astronomical computers” at

the Harvard Observatory. With the funds pro-vided by HENRY DRAPER’s widow, Ann PalmerDraper (1839–1914), Pickering employed Cannon,Fleming, Antonia Maury, Leavitt, and others towork at the observatory. He then supervisedthese talented and well qualified women as theyproduced the contents of the Henry Draper Cata-logue. This catalogue, published in 1918, was pri-marily compiled by Cannon and presented thespectra classification of some 225,000 stars basedon Cannon’s Harvard Classification System, inwhich the stars were ordered in a sequence thatcorresponded to the strength of their hydrogenabsorption lines.

In 1884 Pickering produced a new catalogcalled the Harvard Photometry. This work pre-sented the photometric brightness of 4,260 starsusing the North Star (Polaris) as a reference.Pickering revised and expanded this effort in1908. He was an early advocate of astrophotog-raphy, and in 1903 he published the first photo-graphic map of the entire sky. To achieve his goalsin astrophotography he also sought the assistanceof his younger brother, William Henry Pickering(1858–1938), who established the Harvard Col-lege Observatory’s southern station in Peru. Inde-pendent of the German astronomer HermannVogel (1841–1907), Pickering discovered thefirst spectroscopic binary star system, Mizar, in1889.

He was a dominant figure in American as-tronomy and a great source of encouragement toamateur astronomers. He founded the AmericanAssociation of Variable Star Observers and re-ceived a large number of awards for his contribu-tions to astronomy, including the Henry DraperMedal of the National Academy of Sciences(1888), the Rumford Prize of the AmericanAcademy of Arts and Sciences (1891), the GoldMedal of the Royal Astronomical Society (1886and 1901), and the Bruce Gold Medal of theAstronomical Society of the Pacific (1908). Hedied in Cambridge, Massachusetts, on February3, 1919.

As director of the Harvard College Observatory,Edward Charles Pickering dominated Americanastronomy in the last quarter of the 19th century. He supervised the production of the Henry DraperCatalogue (by Anne Jump Cannon, WilliaminaFleming, Henrietta Leavitt, and other astronomical“computers”) and vigorously promoted the excitingnew field of astrophotography. (AIP Emilio Segrè VisualArchives)

Planck, Max Karl 235

5 Planck, Max Karl(1858–1947)GermanPhysicist

Modern physics, with its wonderful new approachto viewing both the most minute regions of innerspace and the farthest regions of outer space, hastwo brilliant cofounders: Max Planck and ALBERT

EINSTEIN. Many other intelligent people have builtupon the great pillars of 20th-century physics—quantum theory and relativity—but these twogiants of scientific achievement hold the distinc-tion of leading the way.

Planck was born in Kiel, Germany, on April23, 1858. His father was a professor of law at theUniversity of Kiel and gave his son a deep senseof integrity, fairness, and the value of intellectualachievement—important traits that character-ized Planck throughout his life. When Planck wasa young boy, his family moved to Munich, wherehe received his early education. A gifted studentwho could easily have become a great pianist,Planck studied physics at the Universities ofMunich and Berlin. In Berlin he had the oppor-tunity to directly interact with such famous scien-tists as GUSTAV ROBERT KIRCHHOFF and RUDOLF

JULIUS EMMANUEL CLAUSIUS. Kirchhoff intro-duced Planck to sophisticated, classical interpre-tations of blackbody radiation, while Clausiuschallenged him with the profound significance ofthe second law of thermodynamics and the elu-sive concept of entropy.

In 1879 Planck received his doctoral degreein physics from the University of Munich. From1880 to 1885 he remained in Munich as aPrivatdozent (lecturer) in physics at the university.He became an associate professor in physics at theUniversity of Kiel in 1885 and remained in thatposition until 1889, when he succeeded Kirchhoffas professor of physics at the University of Berlin.His promotion to associate professor in 1885 pro-vided Planck with the income to marry his firstwife, Marie Merck—a childhood friend with

whom he lived happily until her death in 1909.The couple had two sons and twin daughters. In1910 Planck married his second wife, Marga vonHösling. He remained a professor of physics at theUniversity of Berlin until his retirement in 1926.Good fortune and success would smile uponPlanck’s career as a physicist in Berlin, but tragedywould stalk his personal life.

Max Planck was the gentle, cultured German physicistwho introduced quantum theory in 1900, transformingphysics and the world in the process. His powerfulnew theory suggested the transport of electromagneticradiation in discrete energy packets or quanta. Amidgreat personal tragedy, Planck received the 1918 NobelPrize in physics for his world-changing scientificaccomplishment—an achievement representing one ofthe two great pillars of modern physics. (The other isAlbert Einstein’s theory of relativity.) (AIP Emilio SegrèVisual Archives)

236 Planck, Max Karl

While teaching at the University of Berlinat the end of the 19th century, Planck began toaddress the very puzzling problem involved withthe emission of energy by a blackbody radiatoras a function of its temperature. A decade ear-lier, JOSEF STEFAN had performed important heattransfer experiments concerning blackbody ra-diators. However, classical physics could not ad-equately explain his experimental observations.To make matters more puzzling, classical elec-tromagnetic theory incorrectly predicted that ablackbody radiator should emit an infinite amountof thermal energy at very high frequencies—aparadoxical condition referred to as the “ultra-violet catastrophe.”

Early in 1900, two British scientists, LordRayleigh (1842–1919) and SIR JAMES HOPWOOD

JEANS, introduced their mathematical formula(called the Rayleigh-Jeans formula) to describethe energy emitted by a blackbody radiator as afunction of wavelength. While their formula ad-equately predicted behavior at long wavelengths(for example, at radio frequencies), their modelfailed completely in trying to predict blackbodybehavior at shorter wavelengths (higher fre-quencies)—the portion of the electromagneticspectrum of great importance in astronomy, sincestars approximate high-temperature blackbodyradiators.

Planck solved the problem when he de-veloped a bold new formula that successfullydescribed the behavior of a blackbody radiatorover all portions of the electromagnetic spec-trum. To reach his successful formula, Planck as-sumed that the atoms of the blackbody bodyemitted their radiation only in discrete indi-vidual energy packets that he called quanta. Ina classic paper that he published in late 1900,Planck presented his new blackbody radiationformula. He included the revolutionary idea thatthe energy for a blackbody resonator at a fre-quency (n) is simply the product h n, where h isa universal constant, now called Planck’s con-stant. This paper, published in Annalen der Physik

(Annals of physics), contained Planck’s most im-portant work and represented a major turningpoint in the history of physics. The introduc-tion of quantum mechanics had profound im-plications on all modern physics from the wayscientists treated subatomic phenomena to theway they modeled the behavior of the universeon cosmic scales.

Yet Planck himself was a reluctant revolu-tionary. For years, he felt that he had only createdthe quantum postulate as a “convenient means”of explaining his blackbody radiation formula.However, other physicists were quick to seizePlanck’s quantum postulate and then to go forthand complete his revolutionary movement—displacing classical physics with modern physics.Einstein used Planck’s quantum postulate toexplain the photoelectric effect in 1905, andNiels Bohr (1885–1962) applied quantummechanics in 1913 to create his world-changingmodel of the hydrogen atom.

Planck received the 1918 Nobel Prize inphysics in recognition of his epoch-making in-vestigations into quantum theory. He also pub-lished two important books: Thermodynamics(1897) and The Theory of Heat Radiation (1906)that summarized his major efforts in the physicsof blackbody radiation. He was a well-respectedphysicist even after his retirement from theUniversity of Berlin in 1926. That same year, theBritish Royal Society honored his contributionsto physics by electing him a foreign member andawarding him its prestigious Copley Medal.

But as Planck climbed to the pinnacle ofprofessional success, his personal life was markedwith deep tragedy. At the time Planck won theNobel Prize in physics, his oldest son, Karl, diedin combat in World War I, and both his twindaughters, Margarete and Emma, died about ayear apart in childbirth.

In the mid–1930s, when Adolf Hitler seizedpower in Germany, Planck, in his capacity as theelder statesperson for the German scientificcommunity, bravely praised Einstein and other

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German-Jewish physicists in open defiance ofthe ongoing Nazi persecutions. Planck even metpersonally with Hitler to try to stop the sense-less attacks against Jewish scientists. But Hitlersimply flew into a tirade and ignored the pleasfrom the aging Nobel laureate. As a final protest,Planck resigned in 1937 as the president of theKaiser Wilhelm Institute—the leadership posi-tion in German science and one in which hehad proudly served with great distinction since1930. In his honor, that institution is now calledthe Max Planck Institute.

During the closing days of World War II,his second son, Erwin, was brutally tortured andthen executed by the Nazi Gestapo for his rolein the unsuccessful 1944 assassination attemptagainst Hitler. Just weeks before the war ended,Planck’s home in Berlin was completely destroyed by Allied bombing. In the very lastdays of the war, U.S. troops launched a daringrescue across war-torn Germany to keep Planckand his second wife, Marga, from being captured by the advancing Russian army. TheDutch-American astronomer GERARD PETER

KUIPER, was a participant in this military action that allowed Planck to live the remain-der of his life in the relative safety of the Allied-occupied portion of a divided Germany. OnOctober 3, 1947, at age 89, the brilliant physicist who ushered in a revolution in physicswith his quantum theory died peacefully inGöttingen, Germany.

5 Plato (Aristocles, Platon)(ca. 427–347 B.C.E.)GreekPhilosopher

The ancient Greek philosopher born Aristoclesin Athens around 427 B.C.E., was not interestedin science. In fact, he is said to have despisedit. Ironically, this pagan philosopher known as Plato—a nickname picked up as a child

because of broad shoulders (from Platon, meaning“broad”)—was the first to create the ideas thatgrew into the science of the universe—a sciencethat would cause the death of many astronomersin the centuries to come who questioned thephilosophies that became the religious “truths”of the Christian church.

Plato was a student of the philosopherSocrates (470–399 B.C.E.), who was a Sophist.This sect of philosophers considered themselves“masters of wisdom,” and traveled from countryto country and town to town as orators espous-ing their philosophies. The Sophist view wasthat there are two kinds of philosophy—naturaland moral. Natural philosophy, that is, nature orscience, was considered a complete waste of timeand mental attention. The only philosophy wor-thy of human thought was moral philosophy be-cause it dealt with the abstract, and abstract wis-dom was the only kind of knowledge that servedto strengthen the soul. Socrates took this viewof moral philosophy one step further, saying themost important knowledge of all was to “knowthyself.” His teachings centered on this premise.

Socrates, Plato, and the others who consid-ered themselves Sophists were changing thethen-accepted views of the Ionians—a sort ofcompetitive group of philosophers. The Ioniansexpanded on the views of Thales (624–546B.C.E.), who declared that the Earth was flatand in essence afloat in an endless sea of space.This notion of a flat planet managed to resur-face some centuries later, and was ultimatelydisproved to the “general public” once and forall—some 2,000 years after its original introduc-tion—by Christopher Columbus. He navigatedhis ships by the stars, and thankfully did not falloff the “edge” of the Earth during any of hisexplorations.

The next evolution of the state of allthings heavenly came from a student of Thalesnamed Anaximander (610–547 B.C.E.). He in-troduced the idea of a sphere around the Earthin which all of the stars were held, and he

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expanded the shape of the Earth from a pan-cake to a cylinder. But since the Ionians werenatural philosophers, not moral philosophers,they were attempting to explain the nature ofthe universe, which the Sophists were adamantlyagainst. In fact, Socrates warned his followersthat if they succumbed to the kind of thinkingsubscribed to by the Ionians, it would “expose[their] mental eyes to total and irreparableblindness.”

In 409 Plato became a disciple of Socrates.When Socrates was executed by the governmentin 399, for “corrupting youth” by teaching themthe “art of words,” Plato left Athens, stating inhis writings that the entire system would re-main corrupt until “kings were philosophers orphilosophers were kings.”

Plato’s travels took him to Italy and Africa.At some point during his journey, he becamefamiliar with the Pythagoreans and their beliefthat everything could be explained with mathe-matics. In Plato’s time, mathematics was notconsidered a science because it dealt withabstracts. As abstract thought, mathematics,then, was the most worthy kind of thought toponder.

In 387 Plato found his way back to Athensand set up the first institute for higher learning.Plato’s Academy, built on land once owned bya man named Academus, was dedicated to ab-stract thought—truly considered higher learn-ing—and since mathematics was purely abstract,Plato became such a proponent of it that he hada sign inscribed above the Academy’s entrancethat read, “Let no one ignorant of mathematicsenter here.” This foundation of mathematicsbuilt into Plato’s teachings was strong enough tohold the philosophy of the cosmos—ideas thatwere proposed initially by Plato then built uponby his most famous student, ARISTOTLE—for thenext 1,500 years.

Plato learned in his travels that Pythagoras(ca. 582–497 B.C.E.) had gone even further withthe sphere concept proposed by Anaximander.

Pythagoras claimed that the entire system wasspherical—the Sun, Moon, stars, and planets—and, by the way, so was the Earth. This was trulya new concept. Plato picked up the cosmic balland ran with it, so to speak, giving credence tothe idea of an entirely spherical universe—a uni-verse that, of course, revolved around the spher-ical Earth. Plato then went one step further still,describing the entire system, in whole and inevery part, as a living organism.

The world according to Plato consisted offour elements—earth, air, fire, and water. Theheavens consisted of one—quintessence. Theperfection of the heavens was a result of the per-fect one who created them. And since the heav-ens were perfect, it stood to reason that they hadto move in the most perfect of paths—in the shapeof a circle. It was reasonable, then, that theyresided in perfect shapes—crystalline spheres—that held everything in place. In fact, Platobelieved that the entirety of the heavens existedin perfect geometric form. With his new ideas onmotion and shape, mathematics and astronomybecame forever intertwined.

Plato’s writings were created as dialogues—discussions between his teacher, Socrates, andone of his students—in which Plato crafted theexplanations of his philosophies. Plato delvedinto the order of the universe in his workTimaeus, in which an astronomer named Timaeusexplains the universe to Socrates. “What is thatwhich always is and has no becoming; and whatis that which is always becoming and neveris? . . . Was the world, I say, always in existenceand without beginning? Or created and had it abeginning?” It is in this writing that Plato putsforth the concept of the circular motions andspherical shape of the universe.

In another dialogue, Republic, Plato deter-mines the order in which the celestial orbs lieclosest to the Earth, but he changes that orderin Timaeus, ultimately settling on the Moon, theSun, Mercury, Venus, and Mars. He describesfour concentric spheres that relate to the four

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elements, and then explains the sizes of thespheres as they relate to the size of Earth. In this,the Earth has a radius of one, water’s radius istwo, air’s radius is five, and fire has a radius of10 and is the sphere that contains the stars. Hethen tells the distances of the spheres of theplanets from the Earth in terms of the numbervalue he has given the four elements. For ex-ample, the distance to the moon is 8, whichequals 1 1 2 1 5, or earth 1 water 1 air.

But Plato’s ideas had many flaws. Forstarters, orbits are not circular, there are no crys-talline spheres holding the universe together,and the entire cosmos does not revolve aroundthe Earth. As his students expanded upon Plato’sideas, complications grew. One such student,Eudoxus of Cnidus, declared that there were 26rotating spheres in the heavens. Another stu-dent, Aristotle, determined that there were infact 54 crystal spheres holding the universe to-gether and keeping it all moving in perfect or-der. As these ideas of the universe expanded, itbecame pretty evident that they did not alwayswork. In order to make sure these philosophiesappeared to work, adjustments had to be made.These adjustments were called “saving the ap-pearances,” and were performed throughout thereign of the geocentric, or Earth-centered, realmthat explained the structure of the universe ac-cording to Aristotle, by way of Plato’s teach-ings. Things did not change until the works ofNICOLAS COPERNICUS, JOHANNES KEPLER, andGALILEO GALILEI became recognized as the truenature of the universe.

In Epinomis, another writing credited toPlato (although there has been controversysurrounding its authorship), a fifth element,aether—the quintessence—was introduced, andit is this writing that is said to bridge the transi-tion from the four elements and Plato’s universeto the expanded view of the cosmos explainedby Aristotle. Here, Plato tells us that the Sun islarger than the Earth, and that the sphere of starsis immense in size.

Plato’s Academy, the first university everestablished, was in operation for 900 years. TheChristian leader, the Roman emperor Justinian,closed the pagan institution in 529. Plato diedat age 82, supposedly peacefully, in his sleep af-ter attending a feast in honor of the wedding ofa student. The crater Plato is located in theAlpine Valley region of the Moon. Nearby liethe craters Eudoxus and Aristoteles.

5 Ptolemy (Claudius Ptolemy, Claudius Ptolemaeus, Claudius Ptolemaios)(ca. 100–178)GreekPhilosopher, Astronomer, Astrologer,Cartographer, Geographer,Mathematician

As with many of the ancients, little is knownabout the famous Greek philosopher ClaudiusPtolemy. Believed to have been a Roman citi-zen, and born in Alexandria, Egypt, he hasbeen described as a man of average build whohad a penchant for horsemanship. It was hismastery of natural (that is, scientific) philosoph-ical thought and writing that made his work theprevailing doctrine of astronomy for approxi-mately 1,500 years after his death, building onmany great thinkers who came before him, includ-ing PLATO, Eudoxus of Cnidus (409–356 B.C.E.),ARISTOTLE, and of course Hipparchus (190–120 B.C.E.).

Ptolemy created ancient encyclopedic vol-umes on astronomy in the dawn of recorded sci-entific study. His goals were very clear in creat-ing his first writing, Megale Mathematike Syntaxis(Great mathematical composition), which cen-turies later became known as Almagest. “We shallset out everything useful for the theory of theheavens in the proper order . . . (and) recountwhat has been adequately established by theancients,” he wrote.

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The “ancients” were the Mesopotamians,whose work was known from about 2,000 yearsprior to Ptolemy’s time. Their studies of the heav-ens included classifications of stars, determiningthe length of seasons, observations and theories oflunar cycles, the relationship between the Moonand planets, planetary observations (particularlyof Venus), and creating the signs of the zodiac thatare familiar today and often credited to Ptolemy.They also determined that the universe was madeup of a system of eight concentric spheres.

Ptolemy was a student of astronomy, and itis generally agreed that Ptolemy’s most influen-tial “teacher” lived years before he was born. Inthe second century B.C.E., Hipparchus (ca. 160–125 B.C.E.) was a highly regarded philosopherand mathematical astronomer who workedmostly on the island of Rhodes, and was the firstperson to use longitude and latitude to designatethe location of a city. Access to Hipparchus’swork was naturally available to Ptolemy throughthe great libraries in Alexandria, as was thework of the philosopher Aristotle, who ex-panded on the work of his teacher Plato, whowas a disciple of Socrates.

One of the biggest distinctions betweenPtolemy and his predecessors is that most of hismajor works have survived. Ptolemy’s writingshave undergone a number of translations through-out the centuries—by Persian mathematician andastronomer Nasir ad-Din at-Tusi (1201–74);philosopher and scholar George of Trebizond(1396–1486), who wrote his own commentary onthe Almagest that was as long as Ptolemy’s work,but whose translation was criticized by the popefor its inaccuracies; and most notably Germanastronomer Johannes Regiomontanus (1436–76),who translated Ptolemy’s work from Greek toLatin from 1460 to 1463, creating Epitome of theAlmagest, the definitive translation of the work forthe 15th and 16th centuries.

Ptolemy’s astronomical work centered on hisbelief that the universe was geocentric in nature;in other words, the Earth was the center of the

universe, around which everything else revolved.This followed Aristotle’s teachings, which hadbecome the accepted view of how the universeworked, despite the fact that, around 287 B.C.E.,ARISTARCHUS OF SAMOS introduced a heliocen-tric model after studying at Aristotle’s Lyceumin Alexandria. This concept fell out of favor andwas not revived until the 16th century, when thePolish cleric NICOLAS COPERNICUS worked onsimplifying Ptolemy’s complicated model of theheavens.

Ptolemy’s work in astronomy was his MegaleMathematike Syntaxis (Great mathematical com-position), simply called Megiste (Greatest), whichwas translated into Arabic as al-Majisti (the great-est), and finally became Almagest. The work con-sists of 13 volumes—a treatise with mathemati-cal computations, observations, and theories onall things regarding the workings of the universe.Ptolemy stated, “We shall try to note downeverything which we think we have discoveredup to the present time.” This included mathe-matical computations for how the geocentricmodel works, using mostly trigonometry, inwhich he defines an approximate value of pi as3.14166, and an introduction to a theorem (nowcalled Ptolemy’s theorem) that states that for aquadrilateral inscribed in a circle (a cyclicquadrilateral), the sum of the products of thetwo pairs of opposite sides are equal to the prod-uct of its two diagonals, written as AC 3 BD 5(AD 3 BC) 1 (AB 3 CD).

In the Almagest Ptolemy explains that theEarth is fixed and the other heavenly spheresrotate around the Earth, and he explains howto predict the positions of the Sun, the Moon,and the planets. He includes his determinationof the length of the year, a theory of the Moon,theory of eclipses, theory of the Sun, theory ofplanets, creates a star catalog with more than1,000 stars, and then creates a very complicatedmodel to fit his observations.

It is very hard to say which part of thiscaused the most trouble for astronomers over the

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centuries. The problems are, of course, based onthe fact that his premise is wrong—the Earth isnot at the center of the universe. Even this wasobvious to Ptolemy; he tried to fix it by movingthe Earth slightly off center from the spheresthat rotated around it.

Other problems arose as well. The value hegave for the length of the year was 3651⁄4—1⁄300

of a day, which is not accurate (the actual valueis less than 1⁄28 of a day). He notes in Almagestthat there are small discrepancies—that hismodel does not match the observed sky. Hestates that everything in the heavens revolves inperfect circular motion.

To give it all some sense, Ptolemy had to dothings like add complicated spheres withinspheres. And while moving the Earth off centerwas a strict violation of Aristotle’s teachings, itseemed to be acceptable because it was onlyslightly different, and with the other adjust-ments, it seemed to work—for the most part. Butit was this kind of fudging that would eventuallyarouse some heated opinions from astronomers incenturies to come. GALILEO GALILEI gave perhapsthe most gentle argument against Ptolemy’smodel in his work Dialogue Concerning the TwoChief World Systems, Ptolemaic and Copernican,written in 1632. SIR ISAAC NEWTON, however,was a little more blatant in his distaste ofPtolemy’s work, saying that Ptolemy was a fraud,and that his work was “a crime committed by ascientist against fellow scientists and scholars, abetrayal of the ethics and integrity of his pro-fession” and that every observation Ptolemywrote in Almagest was completely made up.

Several pieces of the Almagest resulted inspin-off works. Handy Tables gave updated calcu-lations for planetary, solar, and lunar positions,eclipses of the Sun and Moon, and was generallyused for astrology purposes. Planetary Hypothesisconsisted of two books on Ptolemy’s theories of

planetary movement. Astrology was the culmi-nation of Almagest. As Ptolemy saw it, Almagestwas meant to explain how the heavenly bodiesworked, and Astrology explained how they af-fected people’s lives. Other astronomy-related ti-tles were Analemma, which explained the math-ematics necessary to make a sundial, andPlanesphaerium, which delved into how to mapthe celestial sphere onto a plane. Optics, a col-lection of five books, explored light in terms ofreflection and refraction.

Another major contribution to science wasPtolemy’s Geography, a compilation of eightbooks in which he undertakes the daunting taskof giving the coordinates (approximately 8,000)to map the entire known world by longitude andlatitude. The three continents then known wereEurope, Asia, and Africa, and the maps includedthe Tropics of Cancer and Capricorn. His mapsdid not survive, but the text did, and scholars inthe 15th century re-created his maps based onhis instructions in the book.

Almagest gave a historical, philosophical,and scientific perspective on the early views ofastronomy, though it was fraught with mistakes.Even Ptolemy himself knew that the work hadproblems. The complications were huge, and inmany places the text was contradictory. At leastPtolemy felt compelled to address these issues:“Let no one seeing the difficulty of our devices,find troublesome such hypotheses. For it is notproper to apply human things to divine things.”Almagest proposed a view that, unfortunately,became dogma. But it did what Ptolemy said hewas hoping to accomplish: It gave all of the de-tails of what was known at the time. Ptolemyadded original thought about planetary move-ments, created a star catalog that became theprimary source for star maps for the next 1,400years, and most important, defined astronomy asa science.

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R5 Reber, Grote

(1911–2002)AmericanRadio Astronomer

From the beginning of recorded time, amateurastronomers have contributed significantly tothe study of the cosmos. One such astronomerof the 20th century was Grote Reber, a pioneerin radio astronomy.

A graduate of the Illinois Institute ofTechnology in 1933, Reber became intriguedwith the concept of radio astronomy when, dur-ing the same year, Karl Jansky announced hisdiscovery of radio waves emanating from space.The young Reber embarked on his career as anengineer and spent the next 17 years workingfor radio manufacturers in Chicago, giving himthe opportunity to conduct radio research on hisown. Reber spent the summer of 1937 buildinga 31-foot (9-meter) tiltable radio telescope in hisbackyard in Wheaton, Illinois, becoming thefirst person to make such an instrument. Thiswas during the Great Depression, and Reber re-portedly spent six months’ salary for the neces-sary parts and equipment to build the parabolicdish reflector, which he designed himself.

Over the next several years, Reber con-structed three different detectors in an effort tofind radio signals at the right wavelengths. It was

the third receiver that, in 1938, picked up theelusive radio emissions Reber was searching for at160 megahertz. By 1940, and again in 1944, hehad accumulated enough information to publisha series entitled “Cosmic Static” in the Astro-physical Journal, and the study of radio astronomywas officially under way. The year 1944 was abusy one for this important discoverer, as he alsolocated radio emissions coming from the Sun andfrom the nearby Andromeda Galaxy.

Around the middle of the 20th century,Grote Reber moved his operations to an estatein Tasmania, Australia, but first he donated hisoriginal radio telescope to the National RadioAstronomy Observatory in Green Bank, Virginia,where it is still on display. His relocation toTasmania was, as he wrote, to “build a moreelaborate structure capable of being called aradio telescope.” By the time he was through,Reber had constructed an array of 192 dipoles,or antennas, that spanned an area of 3,520 feetin diameter. He focused his efforts on the low-frequency radio waves that he was able to bestreceive in this part of the world.

Reber achieved several firsts in his field. Inaddition to building the first radio telescope,some of his most notable work includes classify-ing radio signals by density and brightness, andusing his findings of radio frequency to create andpublish contour maps of space. This work was

Rees, Sir Martin John 243

significant enough to earn him the CatherineWolfe Bruce Gold Medal, awarded by the Astro-nomical Society of the Pacific in 1962. Reberbecame only the second amateur astronomer toreceive the award since the organization’s begin-nings in 1889.

Reber continued his work in Australia as apioneer in long wavelength radio astronomy.The year 1962 was a big one for accolades inReber’s life. In addition to the Bruce Medal, hereceived an honorary doctorate from OhioState University, the Cresson Gold Medal fromthe Franklin Institute of Pennsylvania, and theAmerican Astronomical Society’s Henry NorrisRussell Lectureship. Additional honors includethe Jansky Prize from the National RadioAstronomy Observatory (NRAO) in 1976, andthe Jackson-Gwilt Medal, in 1983, from theRoyal Astronomical Society.

Beginning in 1938, Reber published morethan 50 papers on his work. “Reber was the firstto systematically study the sky by observingsomething other than visible light,” accordingto Fred Lo, director of the NRAO. Reber’s sci-entific papers are all in the NRAO’s library. Inhis honor, the SETI Institute in Mountain View,California, published a song in their LeagueSongbook to the tune of If You’re Happy and YouKnow It, a short version of the life and times ofthis beloved amateur. On December 20, 2002,Reber died in Australia, just two days before his91st birthday.

5 Rees, Sir Martin John(1942– )BritishAstrophysicist

Sir Martin John Rees was among the firstastrophysicists to suggest that enormous blackholes could power quasars. His investigation ofthe distribution of quasars helped discredit steady-state cosmology. He has also contributed to the

theories of galaxy formation and studied thenature of the so-called dark matter of the uni-verse. Dark matter is matter believed presentthroughout the universe that cannot be observeddirectly because it emits little or no electromag-netic radiation. Contemporary cosmologicalmodels suggest that this “missing mass” controlsthe ultimate fate of the universe. In 1995 Sir Reesaccepted an appointment to serve Great Britainas the 15th Astronomer Royal—a position he stillheld as of 2004.

Rees was born on June 23, 1942, in York,England. He received his formal education at

Sir Martin John Rees, the 15th Astronomer Royal ofGreat Britain, was among the first astrophysicists tosuggest that enormous black holes could powerquasars. His previous investigations of the distributionof quasars helped discredit steady-state cosmology.(AIP Emilio Segrè Visual Archives, John IrwinCollection)

244 Rossi, Bruno Benedetto

Cambridge University. Rees graduated from Trin-ity College in 1963 with a bachelor of arts degreein mathematics and then continued on for hisgraduate work, completing a Ph.D. degree in1967. Before becoming a professor at Sussex Uni-versity in 1972, he held various postdoctoralpositions in both the United Kingdom and theUnited States. In 1973 Rees became thePlumian Professor of Astronomy and Experi-mental Philosophy at Cambridge and remainedin that position until 1991. During this period,he also served two separate terms (1977–82 and1987–91) as director of the Institute of Astronomyat Cambridge. Among his many professionalaffiliations, Rees became a fellow of the RoyalSociety of London in 1979, a foreign associate ofthe United States National Academy of Sciencesin 1982, and a member of the Pontifical Acad-emy of Sciences in 1990. He is currently a RoyalSociety Professor and a fellow of King’s Collegeat Cambridge University. He is also a visitingprofessor at the Imperial College in London.

In 1992 he became president of the RoyalAstronomical Society, and Queen Elizabeth IIconferred knighthood upon him. By royal de-cree in 1995, Sir Martin Rees became GreatBritain’s Astronomer Royal, the 15th distin-guished astronomer to hold this position sincethe English king Charles II created the post in1675.

As an eminent astrophysicist, he has mod-eled quasars and studied their distribution—important work that helped discredit the steady-state universe model in cosmology. He was oneof the first astrophysicists to postulate that enor-mous black holes might power these powerful andpuzzling compact extragalactic objects that werefirst discovered in 1963 by MAARTEN SCHMIDT.Sir Rees maintains a strong research interest inmany areas of contemporary astrophysics, in-cluding gamma ray bursts, black hole formation,the mystery of dark matter, and anthropic cos-mology. One of today’s most interesting cosmo-logical issues involves the so-called anthropic

principle—the somewhat controversial premisethat suggests the universe evolved in just theright way after the big bang to allow for the emer-gence of life, especially intelligent human life.

One of Rees’s greatest talents is his abilityto effectively communicate the complex topicsof modern astrophysics to both technical andnontechnical audiences. He has written morethan 500 technical articles, mainly on cosmol-ogy and astrophysics, and several books, includ-ing Cosmic Coincidences (1989), and Gravity’sFatal Attraction: Black Holes in the Universe(1995); Just Six Numbers (2000), New Perspectivesin Astrophysical Cosmology (2000), and OurCosmic Habitat (2001). Rees has received nu-merous awards for his contributions to modernastrophysics, including the Gold Medal of theRoyal Astronomical Society (1987), the BruceGold Medal from the Astronomical Society ofthe Pacific, the Science Writing Award fromthe American Institute of Physics (1996), theBower Science Medal of the Franklin Institute(1998), and the Rossi Prize of the AmericanAstronomical Society (2000).

5 Rossi, Bruno Benedetto(1905–1993)Italian/AmericanPhysicist, Astronomer, Space Scientist

Attracted to high-energy astronomy, Bruno Rossiinvestigated the fundamental nature of cosmicrays in the 1930s. Using special instruments car-ried into outer space by sounding rockets, he col-laborated with RICCARDO GIACCONI and other sci-entists in 1962 and discovered the X-ray sourcesoutside the solar system. In the first decade of theSpace Age, Rossi made many important contri-butions to the emerging fields of X-ray astronomyand space physics. To honor these important con-tributions, NASA renamed the X-ray astronomysatellite successfully launched in December 1995the Rossi X-ray Timing Explorer (RXTE).

Rossi, Bruno Benedetto 245

Bruno Rossi was born on April 13, 1905, inVenice, Italy. The son of an electrical engineer,he began his college studies at the University ofPadua and received his doctorate in physics fromthe University of Bologna in 1927. He began hisscientific career at the University of Florenceand then became the chair in physics at the Uni-versity of Padua, serving in that post from 1932

to 1938. However, in 1938 the Fascist regime ofBenito Mussolini suddenly dismissed Rossi fromhis position at the university. That year, Fascistleaders went about purging the major Italianuniversities of many “dangerous” intellectualswho might challenge Italy’s totalitarian gov-ernment and question Mussolini’s alliance withNazi Germany. Like many other brilliant Euro-pean physicists in the 1930s, Rossi became apolitical refugee from fascism. Together with hisnew bride, Nora Lombroso, he departed Italy in1938.

The couple arrived in the United States in1939, after short stays in Denmark and theUnited Kingdom. Rossi eventually joined thefaculty at Cornell University in 1940 and re-mained with that university as an associate pro-fessor until 1943. In spring 1943 Rossi’s officialimmigration status as an “enemy alien” waschanged to “cleared to top secret,” and hejoined the many other refugee nuclear physi-cists at the Los Alamos National Laboratory, inNew Mexico. There Rossi collaborated withother gifted scientists from Europe, as they de-veloped the atomic bomb under the top-secretManhattan Project. Rossi used all his skills inradiation detection instrumentation to providehis colleague, the great nuclear physicist EnricoFermi (1901–54), an ultrafast measurement ofthe exponential growth of the chain reaction inthe world’s first plutonium bomb (called Trinity)that was tested near Alamogordo, New Mexico,on July 16, 1945. In a one-microsecond oscil-loscope trace, Rossi’s instrument captured therising intensity of gamma rays from the bomb’ssupercritical chain reaction—marking the pre-cise moment in world history before and afterthe age of nuclear weapons.

After World War II, Rossi left Los Alamosin 1946 to become a professor of physics at theMassachusetts Institute of Technology (MIT). In1966 he became an institute professor—an ac-ademic rank at MIT reserved for scholars ofgreat distinction. Upon retirement in 1971, the

As part of his investigation of cosmic rays in the1930s, the Italian-American physicist Bruno Rossideveloped pioneering electronic instrumentation thatsupported both nuclear particle physics and high-energy astrophysics. He collaborated with Giacconiand others in 1962 and helped discover the first X-raysources outside the solar system. During the firstdecade of the Space Age, Rossi continued to makemade many other important contributions to theemerging fields of X-ray astronomy and space physics. (AIP Emilio Segrè Visual Archives)

246 Rossi, Bruno Benedetto

university honored his accomplishments by be-stowing upon him the distinguished academicrank of institute professor emeritus.

Early in his career, Rossi’s experimental in-vestigations of cosmic rays and their interactionwith matter helped establish the foundation ofmodern high-energy particle physics. Cosmicrays are extremely energetic nuclear particlesthat enter Earth’s atmosphere from outer spaceat velocities approaching that of light. Whencosmic rays collide with atoms in the upper at-mosphere, they produce cascades of numerousshort-lived subatomic particles like mesons.Rossi carefully measured the nuclear particlesassociated with such cosmic ray showers andeffectively turned Earth’s laboratory into onegiant nuclear physics laboratory.

Rossi began his detailed study of cosmic raysin 1929, when only a few scientists had an inter-est in them or realized their great importance.That year, to support his cosmic ray experiments,he invented the first electronic circuit for record-ing the simultaneous occurrence of three or moreelectrical pulses. This circuit is now widely knownas the Rossi coincidence circuit. It not only be-came one of the fundamental electronic devicesused in high-energy nuclear physics research, butalso was the first electronic AND circuit—a ba-sic element in modern digital computers.

While at the University of Florence, Rossidemonstrated in 1930 that cosmic rays were ex-tremely energetic, positively charged nuclearparticles that could pass through a lead shieldover a meter thick. Through years of research,Rossi helped remove much of the mystery sur-rounding the Höhenstrahlung (“radiation fromabove”) first detected by VICTOR FRANCIS HESS

in 1911–12.By the mid-1950s large particle accelerators

had replaced cosmic rays in much of contempo-rary nuclear particle physics research, so Rossiused the arrival of the Space Age (late 1957) tobecame a pioneer in two new fields withinobservational astrophysics: space plasma physics

and X-ray astronomy. In 1958 he focused his at-tention on the potential value of direct meas-urements of ionized interplanetary gases by spaceprobes and Earth-orbiting satellites. He and hiscolleagues constructed a detector (called theMIT plasma cup) that flew into space onboardNASA’s Explorer X satellite. Launched in 1961,this instrument discovered the magnetopause—the outermost boundary of the magnetosphere,beyond which Earth’s magnetic field loses itsdominance.

Then, in 1962, Rossi collaborated withRiccardo Giacconi (then at American Scienceand Engineering, Inc.) and launched a soundingrocket from White Sands, New Mexico, with anearly grazing incidence X-ray mirror as its pay-load. With funding from the U.S. Air Force, thescientists primarily hoped to observe any X-raysscattered from the Moon’s surface as a result ofinteractions with energetic atomic particlesfrom the solar wind. To their great surprise, therocket’s payload detected the first X-ray sourcefrom beyond the solar system—Scorpius X-1, thebrightest and most persistent X-ray source inthe sky. Rossi’s fortuitous discovery of this in-tense cosmic X-ray source marks the beginningof extrasolar (cosmic) X-ray astronomy. Otherastronomers performed optical observations ofScorpius X-1 and found a binary star system,consisting of a visually observable ordinary dwarfstar and a suspected neutron star. In this type ofso-called X-ray binary, matter drawn from thenormal star becomes intensely heated and emitsX-rays as it falls to the surface of its neutron starcompanion.

Rossi was a member of many important sci-entific societies, including the National Acad-emy of Sciences and the American Academy ofArts and Sciences. He was a very accomplishedwriter. Rossi’s books included High Energy Parti-cles (1952), Cosmic Rays (1964), Introduction tothe Physics of Space (coauthored with StanislawOlbert in 1970), and the insightful autobiogra-phy, Moments in the Life of a Scientist (1990). He

Russell, Henry Norris 247

received numerous awards, including the GoldMedal of the Italian Physical Society (1970),the Cresson Medal from the Franklin Institute(1974), the Rumford Award of the AmericanAcademy of Arts and Sciences (1976), and theU.S. National Medal of Science (1985). Rossi’sscientific genius laid many of the foundations ofhigh-energy physics and astrophysics. He diedat home in Cambridge, Massachusetts, onNovember 21, 1993.

5 Russell, Henry Norris(1877–1957)AmericanAstronomer, Astrophysicist

Henry Norris Russell was one of the most influ-ential astronomers in the first half of the 20thcentury. As a student, professor, and observatorydirector, he worked for nearly 60 years at Prince-ton University—a truly productive period thatalso included vigorous retirement activities asprofessor emeritus and observatory directoremeritus. Primarily a theoretical astronomer, hemade significant contributions in spectroscopyand to astrophysics. Independent of EJNAR

HERTZSPRUNG, Russell investigated the relation-ship between absolute stellar magnitude and astar’s spectral class. By 1913 their complemen-tary efforts resulted in the development of thefamous Hertzsprung-Russell (H–R) diagram,which is of fundamental importance to all mod-ern astronomers who wish to understand thetheory of stellar evolution. Russell also per-formed pioneering studies of eclipsing binariesand made preliminary estimates of the relativeabundance of elements in the universe. Oftencalled “the dean of American astronomers,”Russell served the astronomical community verywell as a splendid teacher, writer, and researchadviser.

Russell was born on October 25, 1877, inOyster Bay, New York. The son of a Presbyterian

minister, Russell received his first introductionto astronomy at age five, when his parentsshowed him the 1882 transit of Venus across theSun’s disk. He completed his undergraduate ed-ucation at Princeton University in 1897, gradu-ating with the highest academic honors everawarded by that institution—namely, insignicum laude (with extraordinary honor). Russellremained at Princeton for his doctoral studies inastronomy, again graduating with distinction(summa cum laude) in 1900.

The American astronomer Professor Henry NorrisRussell lecturing at Princeton University. Independentof the Danish astronomer Ejnar Hertzsprung, Russelldeveloped the famous Hertzsprung-Russell (HR)diagram that helps astronomers and astrophysicistsunderstand stellar life cycles. (Courtesy of AIP EmilioSegrè Visual Archives, Margaret Russell EdmondsonCollection)

248 Russell, Henry Norris

Following several years of postdoctoral re-search at Cambridge University, he returned toPrinceton in 1905 to accept an appointment asan instructor in astronomy. He remained affili-ated with Princeton for the remainder of hislife. He became a full professor in 1911 and thefollowing year became director of the PrincetonObservatory. He remained in these positionsuntil his retirement in 1947. Starting in 1921,Russell also held an additional appointment as a research associate of the Mount WilsonObservatory, in the San Gabriel Mountainsjust north of Los Angeles, California. In 1927he received an appointment to the newly en-dowed C. A. Young Research Professorship atPrinceton, a special honor bestowed upon himby his undergraduate classmates from the classof 1897.

Starting with his initial work at CambridgeUniversity on the determination of stellar dis-tances, Russell began to assemble data from dif-ferent classes of stars. He noticed that these datarelated spectral type and absolute magnitude andsoon concluded that there were actually twogeneral types of stars: giants and dwarfs.

The Hertzsprung-Russell (H-R) diagram isactually just an innovative graph that depicts thebrightness and temperature characteristics ofstars. However, since its introduction by Russellat a technical meeting in 1913, it has becomeone of the most important tools in modern as-trophysics. So-called dwarf stars, including theSun, lie on the main sequence of the H-R dia-gram—the well-populated region that runsfrom the top left to lower right portions of thisgraph. Giant and supergiant stars lie in the up-per right portion of the diagram above the mainsequence band. Finally, huddled down in thelower left portion of the H-R diagram belowthe main sequence band are the extremelydense, fading cores of burned-out stars knowncollectively as “white dwarfs.” This term issometimes misleading because it actually ap-plies to a variety of compact, fading stars that

have experienced gravitational collapse at theend of their life cycle.

Following his pioneering work in stellarevaluation, Russell engaged in equally signifi-cant work involving eclipsing binaries. Aneclipsing binary is a binary star that has its or-bital plane positioned with respect to Earth insuch a way that each component star is totallyor partially eclipsed by the other star every or-bital period. With his graduate student HARLOW

SHAPLEY, Russell analyzed the light from suchstars to estimate stellar masses. Later he collab-orated with another assistant, Charlotte EmmaMoore Sitterly (1898–1990), in using statisticalmethods to determine the masses of thousandsof binary stars.

Before the discovery of nuclear fusion,Russell tried to explain stellar evolution interms of gravitational contraction and continualshrinkage and used the H-R diagram as a flow-chart. When HANS ALBRECHT BETHE and otherphysicists began to associate nuclear fusionprocesses with stellar life cycles, Russell aban-doned his contraction theory of stellar evolution.However, the basic information he presented inthe H-R diagram still remained very useful.

In the late 1920s Russell performed a de-tailed analysis of the Sun’s spectrum showingthat hydrogen was a major constituent. He notedthe presence of other elements, as well as theirrelative abundances. Extending this work toother stars, he postulated that most stars exhibita similar general combination of relative ele-mental abundances (dominated by hydrogenand helium) that became known as the “Russellmixture.” This work reached the same generalconclusion that was previously suggested in 1925by the British astronomer Cecilia Helena Payne-Gaposchkin.

Russell was an accomplished teacher, andhis excellent two-volume textbook, Astronomy,jointly written with Raymond Dugan and JohnStewart, appeared in 1926–27. It quicklybecame a standard text in astronomy curricula

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at universities around the world. Russell’s SolarSystem and Its Origin (1935) served as a pioneer-ing guide for future research in astronomy andastrophysics. Even after his retirement fromPrinceton in 1947, Russell remained a domi-nant force in American astronomy. Honoredwith appointments as both an emeritus profes-sor and an emeritus observatory director, hepursued interesting areas in astrophysics for theremainder of his life.

He received recognition from many organi-zations, including the Gold Medal of the RoyalAstronomical Society (1921), the Henry DraperMedal from the National Academy of Sciences(1922), the Rumford Prize from the AmericanAcademy of Arts and Sciences (1925), and theBruce Gold Medal from the AstronomicalSociety of the Pacific (1925). He died in Princeton,New Jersey, on February 18, 1957.

5 Ryle, Sir Martin(1918–1984)BritishPhysicist, Radio Astronomer

Sir Martin Ryle was the British scientist who es-tablished an important center for radio astron-omy at Cambridge University after World WarII. By 1960 his pioneering activities in radio as-tronomy allowed him to introduce the techniqueknown as aperture synthesis. He shared the 1974Nobel Prize in physics with ANTONY HEWISH fortheir pioneering achievements in radio astron-omy, specifically Ryle’s invention of aperturesynthesis and Hewish’s identification of the firstpulsar. Ryle also served Great Britain as the 12thAstronomer Royal from 1972 to 1982.

Ryle was born in Brighton, Sussex, England,on September 27, 1918. Son of a well-respectedphysician, he received education in physics atBradfield College and Oxford University, grad-uating in 1939. During World War II Ryleworked on the development of radar and other

radio frequency systems for the Royal Air Force.His wartime service in the TelecommunicationsResearch Establishment gave him valuable en-gineering experience that he would soon applyin innovative ways in radio astronomy. After thewar Ryle received a fellowship to conduct radiowave research at the Cavendish Laboratory ofthe University of Cambridge. The researchgroup he joined at the laboratory was just start-ing to investigate radio emissions from the Sun.He and his team developed pioneering interfer-ometry techniques to precisely locate radio-emitting regions on the Sun, so other scientistscould correlate the radio frequency emissionswith visible light emissions. These were excitingresearch times, as Ryle began to apply wartimeadvances in radio frequency and electronic tech-nologies to the embryonic field of radio astron-omy. In 1947 he married Rowena Palmer andthe couple eventually had three children: twodaughters and a son.

It was mainly due to Ryle and his colleaguesthat Cambridge became one of the leading cen-ters in the world for astronomical research. In1948 Ryle received an appointment to lecture inphysics at the university, and the following yearhe was elected as a fellow at Trinity College.Between 1948 and 1952 Ryle formed a winningradio astronomy research team that includedHewish. With this team, Ryle started using ra-dio interferometry to carefully map the radiosky—an essential task that led to the establish-ment of radio astronomy as a very fertile fieldfor astronomical research and discovery. He su-pervised the development and publication of aseries of extraterrestrial radio source catalogs. Bythe time the Third Cambridge Catalogue was pub-lished in 1959, it contained the positions andstrengths of more than 500 radio sources. Thisdocument, and timely updates to it, became anessential reference for all radio astronomers.

In the late 1950s Cambridge formally recog-nized the important work Ryle and his team wereaccomplishing in radio astronomy. He became the

250 Ryle, Sir Martin

director of the Mullard Radio Astronomy Obser-vatory in 1957, and then received an appoint-ment to a new chair in radio astronomy. Thispromotion made him the university’s first profes-sor of radio astronomy.

As part of his pioneering efforts in radioastronomy in the 1950s, Ryle learned how to useseveral small radio telescopes to mimic the per-formance of a much larger instrument by selec-tively sampling portions of just the wave frontof interest from an arriving extraterrestrial radiofrequency signal. He called this invention“aperture synthesis” and constructed two majoraperture synthesis radio telescopes at Cam-bridge to support the university’s expandingastronomical effort. These two facilities werecalled the One Mile Telescope and the FiveKilometer Telescope.

Strange, repetitive radio signals collected bythe One Mile Telescope led to the discovery andidentification of the first pulsar by Hewish andhis graduate student, SUSAN JOCELYN BELL

BURNELL, in 1967. The Five Kilometer Telescope,consisting of four movable 13-meter dishes andfour fixed 13-meter dishes, opened in 1972 andsoon became the main instrument of the MullardRadio Astronomy Observatory. It is now called

the Ryle Telescope to honor the pioneeringradio astronomer.

Ryle became a fellow of the Royal Society in1952 and Queen Elizabeth II knighted him in1966. When he shared the Nobel Prize in physicswith Hewish in 1974, they became the first sci-entists to receive this prestigious award forachievements in astronomy. Ryle also served asthe 12th Astronomer Royal of England from1972 to 1982. His most important publicationwas the Third Cambridge Catalogue (1959)—anessential reference in radio astronomy that,among many other contributions, assisted the dis-covery of the first quasar. His other awardsincluded the Gold Medal of the Royal Astronom-ical Society (1964), the Henry Draper Medal ofthe American National Academy of Sciences(1965), the Royal (Gold) Medal of the RoyalSociety (1973), and the Bruce Gold Medal fromthe Astronomical Society of the Pacific (1974).

Ryle died on October 14, 1984, in Cambridge,England. As a pioneer of radio astronomy, hedeveloped revolutionary radio telescope systemsusing aperture synthesis. With these new tele-scopes, he and his colleagues observed some ofthe universe’s most distant galaxies and puzzlingextragalactic objects.

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S5 Sagan, Carl Edward

(1934–1996)AmericanAstronomer, Astrophysicist, Physicist

Perhaps no other person in the 20th century wasas responsible for bringing the science of astro-nomy and space exploration into the public eyeand educating hundreds of millions of peopleworldwide about the nature of the cosmos asCarl Sagan.

Sagan was born in 1934 in Brooklyn, NewYork. In 1951 he entered the University ofChicago, where he received a bachelor’s degreein 1955 and a master’s degree in 1956, both inphysics, and then a Ph.D. in astronomy and as-trophysics in 1960. He then taught at HarvardUniversity through the 1960s and went toCornell University in Ithaca, New York, in 1971,where he remained for the rest of his life.

Sagan’s research highlights were many. Hepostulated the greenhouse effect on Venusbefore space probes proved it. He predicted thatthe apparent seasonal changes on the surface ofMars were the result of windblown dust. Saganidentified organic aerosols on Titan, the majormoon of Saturn. He described in great detail thelong-term environmental consequences of nu-clear war, and he wrote extensively on the ori-gin of life on Earth.

A masterful storyteller and eager host ofinnumerable conferences, meetings, and radioand TV shows, Sagan published more than 600scientific papers and articles and more than 20books. His book Dragons of Eden won the PulitzerPrize in 1978. The paperbound edition of hisbook Pale Blue Dot: A Vision of the Human Futurein Space was a worldwide best seller. His best-selling novel Contact was made into a majormotion picture coproduced by Sagan and hiswife and frequent collaborator, Ann Druyan.All in all, books written or cowritten by Saganwere on the New York Times best-seller list eighttimes.

Sagan’s translation of science into commonlyunderstood terms and concepts is possible bestremembered by his TV series on PBS, Cosmos,an Emmy– and Peabody Award–winning showthat became the most watched series in PBS his-tory, seen by more than 500 million people in60 countries. The accompanying book, Cosmos,was on the New York Times best-seller list for 70weeks and became the best-selling book aboutscience ever published.

Needless to say, Sagan’s awards and hon-orary degrees are almost too numerous to list. Hereceived 22 honorary degrees from Americaninstitutions. For his leading role in NASA’sMariner, Viking, Voyager, and Galileo missionsto other planets, he was awarded NASA medals

252 Scheiner, Christoph

for Exceptional Scientific Achievement andtwice received the Distinguished Public Serviceand the NASA Apollo Achievement Award.Most notable of his other awards are the John F.Kennedy Astronautics Award of the AmericanAstronautical Society; the Explorers Club 75thAnniversary Award; the Konstantin Tsiolkovskymedal of the Soviet Cosmonauts Federation;and the Mazursky Award of the American Astro-nomical Society. He received the highest awardgiven by the National Academy of Sciences, thePublic Welfare Medal. He was DistinguishedVisiting Scientist at the Jet Propulsion Labora-tory in Pasadena, California.

Sagan was editor of Icarus—a professionaljournal devoted to planetary research—for 12years, and was a cofounder of the PlanetarySociety, the largest space-interest organizationin the world, with 100,000 members.

At the time of his death on December 20,1996, of pneumonia resulting from myelodisplasiain a hospital in Seattle, Washington, Sagan wasthe David Duncan Professor of Astronomy andSpace Sciences, and the director of the Laboratoryfor Planetary Studies at Cornell University. Theasteroid 2709 Sagan is named after him.

5 Scheiner, Christoph(1573–1650)GermanAstronomer, Mathematician

Born in Wald, near Mindelheim, in what is nowsouthwest Germany, Christoph Scheiner is bestknown for his protracted controversy withGALILEO GALILEI over the nature of sunspots—Scheiner thought they were shadows cast by theSun’s satellites, while Galileo was convincedthey were irregular phenomena on the Sun’ssurface. In his later years, Scheiner gave in andadmitted that Galileo was right.

As a boy, Scheiner entered the Jesuit Latinschool in Augsburg, then continued his studies

at the Jesuit college in Landsberg before heentered the then-young Jesuit order in 1595.Scheiner studied mathematics, Hebrew, andmetaphysics at the university in Ingolstadt, andin 1610 he joined the faculty at the JesuitCollege in Ingolstadt as a professor of mathe-matics and Hebrew.

At first, Scheiner became an expert in themathematics of sundials, but when the telescopecame into wide use he obtained one and turnedhis studies toward the Sun. Using colored glassand observing for the most part on somewhatfoggy days, Scheiner first observed sunspots in1611. As the chief proponents of traditionalAristotelian cosmology, and hailed by many asthe intellectual champions of the CatholicChurch, the Jesuits and the Catholic Church ingeneral adhered to the “purity” of the universeand PTOLEMY’s geocentric view of the Earth’s po-sition in the heavens. However, the Copernicanheliocentric view was becoming popular, and sci-entists such as Galileo were beginning to provehim right.

Largely because of his religion’s insistencethat the heavens were unchangeable and the Sunwas “virginal,” Scheiner concluded that sunspotswere shadows cast on the Sun’s surface by smallplanets closely circling it inside Mercury’s orbit.Using a pseudonym, he sent three letters to hisfriend Marcus Wexler, an Augsburg banker andJesuit patron, describing his conclusions, andWexler showed the letters, called “Three Letterson Solar Spots,” to Galileo, inviting him tocomment on them.

Thus began a correspondence in which thetwo scientists argued voluminously with one an-other. Galileo, to Scheiner’s consternation, in-sisted that sunspots were actually on the Sun’ssurface, changing their shape and appearing andreappearing at irregular intervals. That the Sunwas not perfect was a heretical position, and con-tributed seriously to Galileo’s falling out withRome and the Jesuit order. Nevertheless, andalthough he seems to have taken pains not to

Schiaparelli, Giovanni Virginio 253

insult Scheiner, Galileo was ultimately provencorrect, and in his publication Rosa Ursina,which was to remain the standard work onsunspots for more than a century, Scheiner even-tually capitulated to Galileo.

After his first observations, Scheiner con-tinued to study sunspots for 15 years, and in RosaUrsina he also described new methods of repre-senting the motions of sunspots across the Sun’ssurface. Scheiner also published several works onatmospheric refraction and performed detailedstudies on the optics of the human eye, describingthe functions of the retina, pupil, and iris. Heelaborated on the previous optical work ofJOHANNES KEPLER, and built what he called a“helioscope” for projecting images of the Sun,improving on the projection methods describedby Galileo and Castelli. This instrument is theearliest known equatorially mounted projector.

While conducting his sunspot research,Scheiner was a mathematics instructor to Arch-duke Maximilian, brother of Emperor RudolphII. This endeared him to royalty and in 1621 hebecame confessor to Archduke Karl, brother ofthe new emperor, Ferdinand II. At this time hefounded a new Jesuit college at Neisse, in Sile-sia. When the archduke died in 1624, Scheinerjourneyed to Rome, remaining there for eightyears and continuing to observe the Sun at theobservatory of the Gregoriana. After chartingthe movements of sunspots, he calculated therotation of the Sun at 25 days near the equatorand 31 days at the poles. Using this informa-tion, he then calculated the equator and therotation axis, discovered solar flares, andobserved the granulation of the photosphere.While in Rome, he published the famous RosaUrsina.

In 1633 Scheiner went back to Bavaria,where he spent the rest of his life in the area ofVienna, both supervising the new college inNeisse and working on a refutation of Copernicantheory. The latter work went virtually unknownand is reported to have little effect on the

Copernicus versus Ptolemy argument. Scheinerdied on June 18, 1650, in Neisse.

5 Schiaparelli, Giovanni Virginio(1835–1910)ItalianAstronomer

Giovanni Schiaparelli was the 19th-centuryItalian astronomer whose misinterpreted wordsstimulated undue excitement about civilizationon Mars. An excellent astronomer, he had care-fully observed Mars in the 1870s and made a de-tailed map of its surface, including some straightmarkings that he dutifully described as canali—meaning “channels” in Italian. Unfortunately,when his description of Martian surface featureswas translated into English, the word canalibecame “canals.” Some astronomers, most no-tably the wealthy American astronomer PERCIVAL

LOWELL, completely misunderstood the true mean-ing of Schiaparelli’s observations and launcheda zealous telescopic search for the supposedcanals that represented the handiwork of aneighboring intelligent alien civilization on theRed Planet.

Schiaparelli was born on March 14, 1835,in Savigliano, Italy. He graduated from theUniversity of Turin in 1854 with a degree in civilengineering. After graduation, he engaged in theprivate study of astronomy, foreign languages,and mathematics. In 1856 he received an ap-pointment to teach mathematics in an elemen-tary school in Turin—an experience that he didnot particularly enjoy. By 1857, government of-ficials of the Piedmont region of Italy recognizedhis talents and interest in astronomy and so theyprovided Schiaparelli with a modest fellowshipto pursue additional efforts in observational as-tronomy. Much to his parents’ dismay, he aban-doned his teaching appointment, accepted thesmall stipend, and studied astronomy underJohann Encke (1791–1865) in Berlin and Otto

254 Schmidt, Maarten

Struve (1819–1905) at the Pulkova Observatoryin St. Petersburg, Russia.

When Schiaparelli returned to Italy in 1860,he became the second astronomer at the BreraObservatory in Milan. Two years later, he becamethe observatory’s director and retained that posi-tion until he retired in 1900. In 1861 Schiaparelli,an exceptionally skilled observer, used the anti-quated equipment he found at the BreraObservatory as best he could and managed to dis-cover the asteroid Hesperia. Over the years hestruggled to upgrade the observatory facilities,while still making significant contributions to as-tronomy. He linked the periodic meteor showercalled the Perseids to the remnants of a comet, andhe conducted observational and theoretical stud-ies concerning the shapes of comet tails. Throughcareful and patient observation, he also showedthat Venus and Mercury rotated very slowly.

He also studied the planet Mars and madedetailed observations during its 1877 opposi-tion, when the Red Planet approached withinabout 56 million kilometers of Earth. Fromthese careful observations, Schiaparelli made adetailed map of Mars, even using his knowledgeof classical literature and the Bible to name var-ious surface features. Schiaparelli’s keen eyefor details caused him to note certain straightfeatures as canali. The mistaken translation ofcanali appearing in Schiaparelli’s 1877 Mars re-port spurred another astronomer, the wealthyLowell, to build a private observatory atFlagstaff, Arizona, and diligently study Mars inan attempt to prove through a set of carefullyselected (but improperly interpreted) observa-tions that the “canals” on Mars were manifes-tations of the presence of an ancient Martiancivilization. Lowell even suggested the un-founded, but very popular, hypothesis that thisrace of Martians was struggling to transport wa-ter from the poles to water-starved regions oftheir dying planet.

Schiaparelli never endorsed Lowell’s exten-sive extrapolation of some of his best work in

solar system astronomy. Yet, this erroneous in-terpretation of his canali in an otherwise excel-lent observational report about Mars is howmost people remember the Italian astronomer.If Schiaparelli had never published his now in-famous 1877 Mars report, he might still havewon many international awards. He receivedthe Gold Medal of the Royal AstronomicalSociety in 1872 and the Bruce Gold Medal fromthe Astronomical Society of the Pacific in 1902.

In 1900 he decided to retire as directory ofthe Brera Observatory because of his failing eye-sight. However, even though he could no longerpractice astronomical observing, he still con-tributed to the field of astronomy by researchingthe history of ancient astronomy and writing thebook Astronomy in the Old Testament in 1903. Hedied on July 4, 1910, in Milan, Italy.

5 Schmidt, Maarten(1929– )Dutch/AmericanAstronomer, Astrophysicist

Modern astronomers are constantly discoveringthat the universe is filled with interesting andstrange objects. In 1963 the joy of discoveringthe unusual touched astronomer MaartenSchmidt as he analyzed the enormous redshift inradio source 3C 273 and found the first quasar.Schmidt’s analysis of the unexpectedly largeredshift in the hydrogen lines of this strangeobject’s spectrum indicated that it was veryyoung and very distant and traveling away fromEarth at more than 15 percent of the speed oflight.

Schmidt was born in Groningen, theNetherlands, on December 28, 1929. He com-pleted his undergraduate education at the Uni-versity of Groningen in 1949 and then earnedhis doctoral degree in 1956 at the University ofLeiden under the research supervision of JAN

HENDRIK OORT. After performing about three

Schmidt, Maarten 255

years of postdoctoral research at the Universityof Leiden, Schmidt came to the United States toaccept an appointment at the California Insti-tute of Technology (Caltech) as a staff memberat the Hale Observatories (Palomar Observa-tory) northeast of San Diego. Schmidt initiallyaccepted this position primarily to continueinvestigating the structure and dynamics of theMilky Way Galaxy. But when the German-American astrophysicist Rudolph Minkowski(1895–1976) retired, Schmidt assumed respon-sibility for his project of taking optical spectraof distant objects that had been found to emitradio wave signals.

At the time, astrophysicists were puzzlingover several compact radio sources, originallyidentified in SIR MARTIN RYLE’s Third CambridgeCatalogue, published in 1959. In the early 1960sthe American astronomer Alan Sandage (b.1926), discovered a mysterious class of radio-loud objects (that is, celestial objects that emitdetectable radio wave signals) with an ultravio-let excess in color. At the time, no one reallyknew what these strange objects might be,because they were starlike in size and had vari-able brightness, yet were radio sources. It was notuntil radio source 3C 273 was identified as oneof these puzzling and bizarre radio sources thatinteresting things began to happen in the astro-nomical community. Astronomers originallycalled the objects “quasi-stellar radio sources”—quasars—because of their starlike appearance(hence “quasi-stellar”) and the fact they werestrong radio sources. However, subsequent dis-coveries forced astrophysicists to change theterm to “quasi-stellar object” (QSO)—expand-ing the meaning to include a compact extra-galactic object that appears like a point sourceof light but emits more energy than 100 or sogalaxies.

In 1963 Schmidt examined the correspon-ding optical spectrum of the brightest quasar,called 3C 273. His insight and calculationshelped unravel this cosmic mystery, and for this

reason he is generally credited with identifyingthe first quasar. He recognized that certain broademission lines in the corresponding optical spec-trum of radio source 3C 273 were actually hy-drogen lines in the Balmer series that had beenredshifted an enormous amount, approximatelythat of an object receding from Earth at about16 percent of the velocity of light. Assumingthat this enormous redshift was the result of anexpanding universe, Schmidt estimated 3C 273to be about a billion light-years away. Thisstrange, compact object was not very far away.It also had the energy output of perhaps 100galaxies.

In 1964 Schmidt became a professor of as-tronomy at Caltech and remained affiliatedwith that institution as of 2004. Following hisbreakthrough work on identifying 3C 273 asthe first quasar, Schmidt studied the evolutionand distribution of quasars throughout the ob-servable universe. He soon discovered thatquasars were more abundant when the universewas younger, a fact that challenged the steady-state universe hypothesis and supported BigBang cosmology. His current research interestscenter around the spatial distribution andluminosity function of quasars in the radio fre-quency, optical, and X-ray portions of the elec-tromagnetic spectrum. He also maintains aninterest in the nature of the extragalactic X-raybackground, the statistics associated withgamma-ray bursts, and the distribution of masswithin the Galaxy.

Since identifying the first quasar in 1963,Schmidt’s astronomical endeavors have earnedhim numerous awards and international recog-nition. These awards include the Rumford Prizeof the American Academy of Arts and Sciences(1968), the Jansky Prize from the NationalRadio Astronomy Observatory of the UnitedStates (1979), the Gold Medal of the RoyalAstronomical Society (1980), and the BruceGold Medal from the Astronomical Society ofthe Pacific (1992). Professor Schmidt continues

256 Schwabe, Samuel Heinrich

to perform creative research at the frontiers ofastrophysics at Caltech.

5 Schwabe, Samuel Heinrich(1789–1875)GermanAstronomer (Amateur)

Professional astronomers are not the only peoplewho have made interesting astronomical discov-eries. Samuel Heinrich Schwabe was a Germanpharmacist who spent most of his free time as anamateur astronomer. Starting in 1825, he beganmaking systematic observations of the Sun andcontinued this activity for many years. He wasprimarily searching for the hypothetical planetof Vulcan believed to be inside the orbit of Mer-cury. However, instead of finding this fictitiousplanet, he discovered that sunspots have a cycleof about 10 years or so. He announced his find-ings in 1843, but German scientists generallyignored his discovery. It was only after thesunspot cycle was rediscovered and confirmed byprofessional astronomers in the 1850s thatSchwabe received some recognition for hisexcellent work.

Schwabe was born on October 25, 1789, inthe town of Dessau, near Berlin, Germany. Hestudied pharmacology in Berlin and then re-turned to Dessau in 1812 to assume managementof his family’s apothecary shop. While studyingto become a pharmacist, Schwabe also becameinterested in astronomy and soon immersed him-self in various astronomical studies as a hobby.In 1825, according to one biographical anec-dote, Schwabe won his first telescope in a lot-tery. He soon ordered a more powerful viewinginstrument from the famous German opticianJOSEPH VON FRAUNHOFER.

In October 1825 Schwabe began his sys-tematic observations of the Sun—a dedicatedeffort that extended for more than 17 years. Hisprimary objective was to discover the planet

Vulcan that some professional astronomers pos-tulated resided close to the Sun inside the orbitof Mercury. While trying to catch a glimpse ofthis nonexistent planet as it traveled across theface of the Sun, Schwabe also noticed andsketched sunspots—thereby establishing a verycareful record of their population and patternsas a function of time. He made very detailedsunspot records, but the sunspots themselveswere of only secondary interest. Weather condi-tions permitting, he observed the Sun almostdaily.

By 1843, however, his quest for Vulcanproved fruitless. At this point, inspirationstruck Schwabe. As he reviewed almost 17 yearsof carefully recorded sunspot data, he suddenlynoticed that there was an approximate 10-year(now established more precisely as 11 years)periodicity in the number of sunspots on thesolar disk. Later that year, he announced thisimportant astronomical observation in an arti-cle titled “Solar Observations during 1843” thatappeared in the German journal AstronomischeNachrichten. At first, the German scientificestablishment completely ignored Schwabe’sdiscovery, possibly because he was an amateurastronomer with no formal academic status inphysics or astronomy.

But Schwabe’s careful record of sunspots andhis conjecture about an apparent 10-year perio-dicity emerged out of obscurity and gainedlong-overdue scientific recognition in 1851when the famous German naturalist BaronAlexander von Humboldt (1769–1859) in-cluded these data in the third volume of hismonumental work, Kosmos, a vast encyclopediaof natural knowledge. Once Humboldt recog-nized the value of Schwabe’s work, other scien-tists immediately began to examine the sunspotcycle and to relate the periodicity of solar activ-ity to geomagnetic activity of Earth. In a veryreal sense, this rediscovery of Schwabe’s sunspotcycle hypothesis represents the beginning ofmodern solar-terrestrial physics. Schwabe, the

Schwarzschild, Karl 257

pharmacist-astronomer, personally likened hisserendipitous discovery to the biblical accountof Saul, who went out in search of his father’sdonkey and found a kingdom.

In 1831 Schwabe became the first as-tronomer, amateur or professional, to provide adetailed description and drawing of Jupiter’sGreat Red Spot. The British Royal AstronomicalSociety awarded Schwabe its prestigious GoldMedal in 1857 and elected him as a foreignmember in 1868—an honor rarely bestowed onan amateur astronomer. He died in Dessau,Germany, on April 11, 1875. As part of hislegacy to astronomy, the Swiss astronomerJohann Rudolf Wolf (1816–93) immediatelybuilt upon Schwabe’s many years of detailed so-lar disk observations and was able to announcein 1857 a refined value for sunspot periodicityat slightly more than 11 years.

5 Schwarzschild, Karl(1873–1916)GermanAstronomer, Astrophysicist

Karl Schwarzschild was the talented German as-tronomer who started black hole astrophysics.He did this by applying ALBERT EINSTEIN’s rela-tivity theory to a very high-density object: apoint mass. In 1916 while voluntarily serving inthe German army in Russia, he developed theconcept of the Schwarzschild radius—the zoneor “event horizon” around a superdense, gravi-tationally collapsing star from which nothing,not even light itself, can escape.

He was born in Frankfurt, Germany, onOctober 9, 1873. The son of a prosperous Jewishbusinessman, Schwarzschild showed his mathe-matical aptitude and interest in astronomy earlyin life. At age 16 he published a significant ce-lestial mechanics paper that addressed theproblem of binary orbits. Encouraged to pursuea scientific career, he began his studies at the

University of Strasbourg and then transferred tothe University of Munich in 1893, completinghis doctor of philosophy degree there in 1896.

After graduation Schwarzschild worked inVienna from 1896 to 1899 at the KuffnerObservatory. He then spent some time lecturingand writing before he joined the faculty at theUniversity of Göttingen in 1901 as an associateprofessor. He remained at the university until1909, quickly reaching rank of full professor and

The German astronomer Karl Schwarzschild poseshere in full academic regalia early in the 20th century.Decades ahead of his time, Schwarzschild brilliantlyapplied Einstein’s relativity theory to very high-densityobjects and singularities (point masses)—therebystarting black hole astrophysics. In 1916 he introducedthe idea of an event horizon (now called theSchwarzschild radius) around a super-dense,gravitationally collapsing star, from which nothing,not even light, can escape. (Photo by Robert Bein,courtesy AIP Emilio Segrè Visual Archives)

258 Secchi, Pietro Angelo

becoming the director of the observatory.During this period, he explored the possibilitythat space might be non-Euclidean (that is,have curvature), he investigated radiative equi-librium processes in the Sun’s outer atmosphere,and he promoted the use of astrophotography—particularly to support the study of the rela-tionship between a star’s spectral type and itscolor.

In 1909 he left the University of Göttingento accept the position of director of theAstrophysical Observatory at Potsdam. Althoughalready in his early 40s when World War I brokeout, he volunteered for military service in theKaiser’s imperial army. Starting in 1914, heserved with the German army in Belgium,France, and finally Russia. While on duty inRussia in 1916, he stayed in touch with scien-tific developments by writing two excellent pa-pers that dealt with Einstein’s newly introduced(1915) general theory of relativity. One ofSchwarzschild’s papers presented the first exactsolution of Einstein’s general gravitational equa-tions, providing a description of how gravitycurves space and time around a single, very com-pact object. In his second paper, Schwarzschildintroduced the concept of the event horizonaround a black hole, beyond which nothing, noteven light, can escape. Schwarzschild demon-strated that according to general relativity, if anobject’s gravity is sufficiently strong, the space-time continuum around that body becomes sohighly curved and warped that light itself can-not escape from the object. He further explainedthat this condition occurs when the radius of amassive body is less than a certain critical value,now called the Schwarzschild radius. Today, as-trophysicists call the Schwarzschild radius the“event horizon” or “boundary of no return” fora black hole. Anything that falls inside this ra-dius can never escape. The event horizon repre-sents the start of a special region that is totallydisconnected from normal space and time.Schwarzschild’s papers, written weeks before his

death, represent the theoretical start of blackhole astrophysics.

Unfortunately, the brilliant German as-tronomer contracted a fatal skin disease whileserving in Russia during World War I. TheGerman army discharged the stricken scientistand shipped him home, where he died shortlyafter his return to Potsdam, on May 11, 1916.However, his son, the German-born Americanastrophysicist Martin Schwarzschild (1912–97),would continue making important contributionsto astronomy. Following in his father’s scientificfootsteps, Martin left Germany after WorldWar II and became a professor at PrincetonUniversity, where he pioneered the use of digi-tal computers to perform theoretical studies ofstellar structure and evolution.

5 Secchi, Pietro Angelo(1818–1878)ItalianAstronomer, Spectroscopist

The 19th-century astronomer and Jesuit priestPietro Angelo Secchi was the first person to sys-tematically apply spectroscopy to astronomy. Bythe mid-1860s he completed the first major as-tronomical spectroscopic survey and then pub-lished a catalog that contained the spectra ofmore than 4,000 stars. After examining thesedata, in about 1867 he placed stellar spectra intofour basic classes. This represented what was laterreferred to as the Secchi classification system. Healso supported advances in astrophotography,primarily by photographing solar eclipses—pio-neering work that assisted in the study of solarphenomena such as prominences.

Secchi was born on June 29, 1818, in theLombardian town of Reggio, Italy. In 1833 heentered a religious order known as the Societyof Jesus (Jesuits), and began lecturing on physicsand mathematics at the Jesuit Roman Collegein 1839. He started his formal theological stud-

Shapley, Harlow 259

ies in 1844 and was ordained as a priest in theRoman Catholic Church in 1847. Due to ex-treme antireligious political unrest that occurredin Rome in 1848, he left Italy and traveled toGreat Britain and then on to the United States,where he taught natural sciences at GeorgetownUniversity in Washington, D.C. By 1849 orderwas restored in Rome and Secchi returned tobecome a professor of astronomy and the direc-tor of the observatory at the Roman College.Finding the old observatory in great disrepairand poorly equipped, he started construction ofa new observatory dome on top of the firm vaultof the Church of Saint Ignatius at the college.From this refurbished observatory he becameone of the first astronomers to carry out researchthat concentrated on the physical properties ofthe stars rather than simply their positions. Healso conducted pioneering work in meteorologyand terrestrial magnetism.

Soon after ROBERT WILHELM BUNSEN andGUSTAV ROBERT KIRCHHOFF introduced theconcept of astronomical spectroscopy in theearly 1860s, Secchi became the first astronomerto adapt spectroscopy to astronomy in a rigor-ous, systematic manner. In the mid-1860s heconducted the first spectroscopic survey of theheavens by using visual observation to theirspectra to classify more than 4,000 stars. He di-vided these stars into four general groups, in-troducing a system that later became known asthe Secchi classification. His pioneering workanticipated the more precise photographicwork of EDWARD CHARLES PICKERING, ANNIE

JUMP CANNON, and others who developed theHarvard Classification System, which appearedin the 1890s.

Secchi was also extremely active in solarphysics. He investigated prominences during so-lar eclipses, using both visual and spectroscopicobservations. He proved that prominences werefeatures on the Sun itself and not an ancillaryphenomenon associated with the Moon or theeclipse period. His influential monograph Le

Soleil (The Sun) first appeared in Paris in 1870.Secchi enjoyed a wide international reputationas a skilled observer and excellent astronomer.He was consequently allowed to operate his ob-servatory in Rome despite the political turmoiland anti-Jesuit politics that swept Italy in theearly 1870s. He enjoyed membership in theBritish Royal Society, the Royal AstronomicalSociety, the French Academy of Sciences, andthe Imperial Russian Academy of St. Petersburg.Pietro Secchi, a true pioneer of astronomicalspectroscopy, died in Rome on February 26,1878.

5 Shapley, Harlow(1885–1972)AmericanAstronomer

Early in his career, astronomer Harlow Shapleysingle-handedly more than doubled the size ofthe known universe in 1914, when he used a de-tailed study of variable stars (especially Cepheidvariables) to establish more accurate dimensionsfor the Milky Way Galaxy. He discovered thatthe Sun was actually two-thirds of the way outin the rim of our spiral galaxy. Up until then,astronomers assumed the Sun enjoyed a favoredlocation near the center of the Galaxy. In 1920Shapley engaged in a well-publicized, thoughinconclusive, debate with fellow astronomerHEBER DOUST CURTIS concerning the nature ofdistant spiral nebula and the true size of theMilky Way Galaxy. As director of the HarvardCollege Observatory, Shapley made many use-ful contributions to astronomy, including stud-ies of the Magellanic Clouds and clusters ofgalaxies.

Shapley was born on November 2, 1885, inNashville, Missouri. He started out in professionallife as a journalist and then decided to switch toastronomy. He changed careers during that ex-citing and intellectually turbulent period in the

260 Shapley, Harlow

early part of the 20th century when great astro-nomical discoveries, including his importantcontributions, displaced the Sun from its long-assumed position near the center of the Galaxy.Astronomers also recognized that the Milky WayGalaxy was but one of millions of others in a

vast expanding universe. Prior to entering theUniversity of Missouri, Shapley had worked fortwo years as a newspaper reporter. However,once exposed to astronomy during his under-graduate education, he embraced the field andquickly became one of its rising young stars. Hecompleted his undergraduate degree in astron-omy at the University of Missouri in 1910,followed a year later by his master of arts degreefrom the same institution. Shapley then went toPrinceton University where he studied for hisPh.D. under the great American astronomerHENRY NORRIS RUSSELL.

Shapley’s doctoral research involved a care-ful study of the orbits of 90 eclipsing binaries. Itwas a major effort, supervised by Russell, throughwhich Shapley essentially created a specialbranch of binary star astronomy. In the processof completing his doctoral research, Shapleydistinguished Cepheid variables from eclipsingbinaries and then correctly suggested Cepheidvariability was due to pulsations.

Following completion of his doctoral degreein 1914, Shapley worked at the Mount WilsonObservatory, near Los Angeles, California, until1921. There he investigated globular clustersand was able to calibrate the period-luminosityrelation for Cepheid variables discovered byHENRIETTA SWAN LEAVITT in 1912. He boldlyand correctly postulated that the distribution ofthese globular clusters served as an outline forthe Milky Way Galaxy. Using Cepheid variablesas an astronomical “yardstick,” he speculatedthat the Milky Way Galaxy was actually muchlarger than previously believed. He further notedthat because of the observed asymmetric distri-bution of these globular clusters, the Sun wasnot near the center of the Galaxy, as had beenassumed, but rather resided many light-yearsaway from the center. Shapley, initially unawareof the dimming influence of interstellar gas anddust, estimated that the Sun was about 50,000light-years from the galactic center. He later cor-rected this overestimate and placed the Sun at

The American astronomer Harlow Shapley at his deskat the Harvard College Observatory. In 1914 Shapleystarted a detailed study of variable stars in an effort toestablish more accurate dimensions for the Milky WayGalaxy. This work encouraged him to engage in agreat public debate with fellow astronomer HeberCurtis. They disagreed about the actual size of theMilky Way and the true nature of distant spiralnebulas. In 1929, however, Edwin Hubble presentedhis hypothesis of an expanding universe filled withspiral and other types of distant galaxies, collapsingmany of Shapley’s key debate points and resolving thehighly contested discussions. (AIP Emilio Segrè VisualArchives, Shapley Collection)

Shapley, Harlow 261

about 30,000 light-years from the galacticcenter—a value independently confirmed byJAN HENDRIK OORT and now generally accepted.Shapley’s pioneering work at Mount Wilson alsoprepared him to participate in debates about thesize of the Galaxy and the true nature of distantspiral galaxies.

Many astronomers, including Shapley, op-posed Curtis’s hypothesis about the extragalac-tic nature of spiral nebulas. On April 26, 1920,Curtis and Shapley engaged in their famous“Great Debate” on the scale of the universe andthe nature of the Milky Way Galaxy at theNational Academy of Sciences in Washington,D.C. At the time, the vast majority of as-tronomers considered the extent of the MilkyWay Galaxy synonymous with the size of theuniverse—that is, most thought the universewas just one big galaxy. However, because ofincomplete knowledge, neither astronomer in-volved in this highly publicized debate was com-pletely correct. Curtis argued that spiral nebu-las were other galaxies similar to the MilkyWay—a bold hypothesis later proven to becorrect—but he also suggested that the Galaxywas small and that the Sun was near its center,both of which ideas were subsequently provenincorrect. Shapley, on the other hand, incor-rectly opposed the hypothesis that spiral nebu-las were other galaxies. He argued that theGalaxy was very large (in fact, much larger thanit actually is) and that the Sun was far from thegalactic center.

It was not until the mid-1920s that the greatAmerican astronomer EDWIN POWELL HUBBLE,helped resolve one of the main points of con-troversy. He did this by using the behavior ofCepheid variable stars to estimate the distanceto the Andromeda Galaxy. Hubble showed thatthis distance was much greater than the size ofthe Milky Way Galaxy proposed by Shapley. So,as Curtis had suggested, the great spiral nebulain Andromeda, like other spiral nebulas, couldnot be part of the Milky Way and therefore must

be separate. In the 1930s astronomers such asOort proved that Shapley’s comments were moreaccurate concerning the actual size of the MilkyWay and the Sun’s relative location within it.Therefore, when viewed from the perspective ofscience history, both eminent astronomers hadinconclusively argued their positions using par-tially faulty and fragmentary data. The mostimportant consequence of the Curtis-Shapleydebate was that it triggered a new wave of as-tronomical inquiry in the 1920s. This burst ofinquiry encouraged astronomers, Hubble amongthem, to determine the true size of the MilkyWay and to recognize that it is but one of manyother galaxies in an incredibly vast, expandinguniverse.

Upon the death of EDWARD CHARLES

PICKERING, Shapley was offered the directorshipof the Harvard College Observatory. He ac-cepted, left Mount Wilson in 1921, and remainedas the director of the Harvard Observatory untilhis retirement in 1952. During his directorship,Shapley created an outstanding graduate schoolin astronomy, performed his own studies of theMagellanic Clouds, and wrote many interestingarticles and books about astronomy, includingthe popular autobiographical work ThroughRugged Ways to the Stars (1969). In the 1930sShapley discovered the first two dwarf galaxieswithin the Local Group and also discovered thegrouping of clusters of galaxies, or superclus-ters—the most prominent of which is now calledthe Shapley concentration.

Shapley’s contributions to astronomy earnednumerous awards, including the Henry DraperMedal of the National Academy of Sciences(1926), the Rumford Prize of the AmericanAcademy of Arts and Sciences (1933), the GoldMedal of the Royal Astronomical Society (1934),and the Bruce Gold Medal of the AstronomicalSociety of the Pacific (1939). The astronomerwho helped displace the Sun from its historicallyassumed position near the center of the universedied in Boulder, Colorado, on October 20, 1972.

262 Sitter, Willem de

5 Sitter, Willem de(1872–1934)DutchAstronomer, Mathematician

Willem de Sitter was born May 6, 1872, atSneek, in Friesland, a province in the northernpart of the Netherlands. His early education wasat the Gymnasium at Arnhem, where his fatherwas a judge. In 1891 he entered the Universityof Groningen, where he intended to study math-ematics. However, while there he became inter-ested in physics and astronomy and worked inthe Groningen Astronomical Laboratory, thenunder the direction of the famous ProfessorJACOBUS CORNELIUS KAPTEYN.

In 1896 SIR DAVID GILL, who was the Royal(British) Astronomer at the observatory at theCape of Good Hope, South Africa, paid a visitto Kapteyn at the Groningen laboratory and wasintroduced to de Sitter as one of Kapteyn’s bril-liant mathematics students. At the time, deSitter was at a measuring instrument, makingcomputations on a photographic plate. The fol-lowing morning, de Sitter was having breakfastin his room when he received a summons tomeet with Gill in the laboratory. There, withMrs. Kapteyn acting as interpreter, Gill invitedde Sitter to visit the South African observatoryand offered him a job as assistant. After ex-plaining that he was a mathematician and notan astronomer, and requesting (and receiving)another year’s time in order to complete his doc-toral degree, de Sitter agreed. Thus was born theastronomy career of de Sitter.

Arriving at the Cape observatory in August1897, de Sitter began his initial work in parallaxand triangulation computations with a heliome-ter. He observed the colors of stars and was firstto determine that stars near the plane of theMilky Way are always bluer than those away fromthe plane. But his main interest soon became ob-servations of the moons of Jupiter. Combining

his mathematical talents and his newly acquiredastronomy techniques, de Sitter studied the mo-tions of the major moons of Jupiter and calcu-lated their masses and the mass of Jupiter itself.

After working with Gill for more than twoyears, de Sitter returned to the GroningenAstronomical Laboratory. In 1908 he was ap-pointed professor of astronomy at the Uni-ver-sity of Leiden, the oldest university in theNetherlands, established in 1575, and whoseobservatory, established in 1633, is the oldestoperating university observatory in the world.

In this position, de Sitter made observa-tions in 1913 of double-star systems and becamethe first astronomer to prove that the velocityof light had nothing to do with the velocity ofits source. Also while at Leiden, de Sitter be-came familiar with the newly promulgated the-ory of general relativity of ALBERT EINSTEIN,then director of the Kaiser Wilhelm Instituteof Physics in Berlin. Einstein visited de Sitterat Leiden, but the political situation in Europe,as war was fast approaching, prevented the twoscientists from working together. Einstein be-gan sending his correspondence to de Sitter,who in turn sent them to SIR ARTHUR STANLEY

EDDINGTON at the Royal Observatory inGreenwich, England.

De Sitter then published a series of three pa-pers entitled “On Einstein’s Theory of Gravitationand Its Astronomical Consequences.” The firsttwo papers explained Einstein’s theories, and thethird proposed his own interpretation of the as-tronomical consequences of Einstein’s theory.One biographer states that while Einstein, whoknew little of astronomy, wondered how astron-omy could be applied to his theory, de Sitter be-came the first scientist to apply the theory ofgeneral relativity to astronomy. Indeed, deSitter’s solution in 1917 to Einstein’s field equa-tions showed that a practically empty universewas expanding, instead of contracting, as was thecommon theory at the time.

Somerville, Mary Fairfax 263

Later, with the war over and the politicalclimate eased, de Sitter and Einstein publisheda joint paper in which they proposed there maybe in the universe large amounts of matter thatdoes not emit light and consequently has notbeen detected. This became known as “darkmatter” and has since been shown to exist; how-ever, its exact nature is still under investigation.

In 1919 de Sitter was named director of theLeiden Observatory and, under the guidance ofKapteyn, expanded and modernized it adding anastrophysical division dedicated to the spec-troscopy and photometry of stars, and a theo-retical division, which he headed himself. DeSitter also had the wisdom to hire EJNAR

HERTZSPRUNG, who would succeed him andco-invent the famous Hertzsprung-Russell dia-gram of stars, still in use today. While directorat Leiden, de Sitter also hired the man whowould become the most famous of all Leidenastronomers, JAN HENDRIK OORT.

De Sitter was awarded the Watson Medal ofthe National Academy of Science in 1929, theBruce Gold Medal of the Astronomical Societyof the Pacific and the Gold Medal of the RoyalAstronomical Society in 1931. During the pe-riod 1925–28 he was president of the Inter-national Astronomical Union.

The chance meeting in 1896 of Gill and deSitter changed the course of the latter’s life frommathematics to theoretical astronomy and gavethe world new knowledge of Jupiter and itsmoons and the first interpreter and analyst ofEinstein’s revolutionary theories. De Sitter diedof pneumonia on November 19, 1934, atLeiden.

5 Somerville, Mary Fairfax(1780–1872)BritishAstronomer, Geographer,Mathematician

Self-taught, with only one year of formal edu-cation at a boarding school when she was 10years old, the prolific Mary Somerville becameone of the most scientifically influential personsof the 19th century and, as one contemporaryobserver put it, “one of the most remarkablewomen of her generation.”

She was born in 1780 at Jedburgh, Rox-burghshire, Scotland, to Margaret Charters Fair-fax and naval officer Sir William George Fairfax,who later became vice-admiral of the Scottishnavy. However, Jedburgh was just a stopover; thefamily home was in Burntisland, in the county ofFife.

The social mores of the time dictated thatboys got the education and girls learned needle-point. Somerville’s mother did teach her to read,using the family Bible, but saw no reason for herdaughter to learn how to write. When she was10, Somerville was sent to Miss Primrose’sBoarding School, where she spent a dismal andunhappy year, but did learn to write. When shereturned home, she had such a craving forknowledge that she began to read every book inthe house, to the point where she was criticizedby family members for her “unladylike” preoc-cupation. Consequently, she was sent to a spe-cial school to learn needlework. She also tookpiano lessons and had lessons in painting fromthe artist Alexander Naysmyth.

Visiting an uncle in Jedburgh, Mary casuallymentioned to him that she was teaching herselfLatin. The uncle, perhaps the only family mem-ber to appreciate her quest for knowledge, en-couraged her, and together they studied Latinwhenever she visited.

In her early teens she became interested inmathematics when her art teacher, Naysmyth,taught her the basics of perspective in paintingby using Euclid’s Elements. She immediatelyread the whole book, which led to her interestin astronomy. However, it was not proper foryoung ladies to buy science books in those days,so Somerville prevailed upon her brother to

264 Somerville, Mary Fairfax

smuggle her his science books. She also beganvisiting her brother’s tutor to learn more.

Her next passion was algebra. While read-ing puzzles in a friend’s woman’s magazine, shefound her curiosity piqued by the strange sym-bols in an algebra problem, and she borrowedalgebra texts from the tutor. She became so im-mersed in algebra and other mathematicalbranches that her parents worried about herhealth.

At age 24 she married a Russian naval offi-cer, Samuel Grieg, who had a low opinion ofher interest in education. They settled inLondon, and when Grieg died, only three yearslater, he left her financially independent andshe seized her newfound free time to pursue herinterest on her own. Now the mother of twochildren, she had a circle of friends in Londonwho encouraged her pursuit of science, includ-ing a professor of natural philosophy at EdinburghUniversity named John Playfair, who intro-duced her by mail to William Wallace, a pro-fessor of mathematics at the Royal MilitaryCollege at Great Marlow. In their letters hetaught her how to solve mathematical problemsto the point where she eventually won a silvermedal for her solution to a problem publishedin Mathematical Repository. In accepting themedal, she sought the advice of the editor of themagazine for the proper course of mathematicalstudy, which led to her reading of SIR ISAAC

NEWTON’s Principia and PIERRE SIMON MARQUIS

DE LAPLACE’s Mécanique Celeste, as well as sev-eral other prominent astronomical and mathe-matical textbooks.

In a big turning point in her life, she mar-ried William Somerville in 1812. He was a sur-geon in the Royal Navy who was supportive ofher interest in science. By this time Somervillealso was fluent in French and Greek, and inEdinburgh both she and her husband studied ge-ology and traveled in a close circle of physicistsand mathematicians. William Somerville wastransferred to London and accepted into the

Royal Society, which led them into another tightcircle of the leading scientists of the day associ-ated with the University of Cambridge andseveral prominent scientific societies, both inLondon and on the Continent.

Somerville published her first paper in1826, at age 46: “The Magnetic Properties ofthe Violet Rays of the Solar Spectrum.” It at-tracted interest at the time, but its premise waseventually refuted. However, it gained her herfirst attention as a serious scientific investiga-tor, and the next year Lord Brougham, of theSociety for the Diffusion of Useful Knowledge,asked Somerville to translate Mécanique Celestefor popular consumption. Instead, she explainedin minute detail the mathematics used by theFrenchman Laplace, which was unfamiliar tomost English mathematicians of the day. Her“translation” eventually became a ponderoustome, too big for the society to publish, and itwas published in 1831 as The Mechanism of theHeavens.

The book was a smashing success bothcritically and financially, and boosted her rep-utation immensely. She spent a year in Paris,meeting even more prominent scientists, andwrote her second book, The Connection of thePhysical Sciences. Her discussion in the book ofa theoretical planet perturbing Uranus led JOHN

COUCH ADAMS to his discovery of Neptune.This produced a shower of honors. She andCAROLINE LUCRETIA HERSCHEL were the firstwomen elected to the Royal AstronomicalSociety in 1835. The Société de Physique etd’Histoire Naturelle de Genève gave her an hon-orary membership, and the Royal Irish Academydid the same.

In 1838 William’s health deteriorated andthe family moved to Italy, where William sur-vived for 22 more years while Mary wrote booksat a prolific rate. Her most important later pub-lication was Physical Geography, which was pub-lished when she was 68, in 1848, and it becameher most successful textbook, used in secondary

Slipher, Vesto Melvin 265

schools and universities until the turn of the20th century. This book got her elected to theAmerican Geographical and Statistical Societyand the Italian Geographical Society. In 1870,at 90 years of age, she received the Victoria GoldMedal of the Royal Geographical Society.

Somerville did more to publicize mathe-matics and astronomy than any other woman ofher time, and, for obvious reasons, was a devoutsupporter of women’s suffrage and women’s ed-ucation. When John Stuart Mill, the greatBritish philosopher and economist, encouragedthe British parliament to give women the vote,he amassed a huge petition to submit to them.The first name on his list was Mary FairfaxSomerville.

5 Slipher, Vesto Melvin(1875–1969)AmericanAstronomer

Behind many great scientific breakthroughs,there is usually some generally unrecognizedpathfinder who first marked the trail for othersto travel and achieve technical glory. Theastronomer Vesto Slipher was the pathfinder forthe famous American astronomer EDWIN POW-ELL HUBBLE. In 1912 Slipher began his impor-tant series of spectroscopic studies involving thelight from objects called “spiral nebula” at thetime, which are now recognized as distantgalaxies. He noticed that the spectroscopic datahe collected at the Lowell Observatory exhib-ited interesting Doppler shift phenomena. Thepredominant number of spectral redshifts heobserved in the spiral nebulas under study sug-gested that these objects were receding fromEarth at very high speed. Although his datawere generally ignored when he presented themin the late 1910s, his pioneering spectroscopicstudies provided the framework around whichHubble and other astronomers eventually

developed the modern concept of an expandinguniverse.

Slipher was born on November 11, 1875, inMulberry, Indiana. He received all his educa-tion at the University of Indiana atBloomington. There he received his bachelor ofarts degree in mechanics and astronomy in1901, his M.A. degree in 1903, and his Ph.D.degree in 1909.

In August 1901 Slipher started working atthe Lowell Observatory, in Flagstaff, Arizona. He

The American astronomer Vesto Slipher worked atthe Lowell Observatory and in about 1912 performedthe initial spectroscopic studies of spiral nebulas(galaxies) that revealed Doppler redshifts. His workbecame the foundation upon which Edwin Hubbleand others pursued the concept of an expandinguniverse. Later, as director of the Lowell Observatory,he hired a young Kansas farm boy, Clyde Tombaugh,and assigned him the arduous task of searching forPercival Lowell’s Planet X. Tombaugh delivered onFebruary 18, 1930, when he discovered the planetPluto. (AIP Emilio Segrè Visual Archives)

266 Slipher, Vesto Melvin

became the assistant of the observatory in 1915,and when PERCIVAL LOWELL died in 1916, Slipherbecame the acting director of the observatory. In1926, he became its director and served in thatposition until his retirement in 1954.

Slipher was not only an excellent spectro-scopist but he also proved to be a competentadministrator. One of his early decisions as di-rector was to hire a young farm boy named CLYDE

WILLIAM TOMBAUGH in the late 1920s and as-sign him the task of searching the night skies forLowell’s Planet X. On March 13, 1930, in hiscapacity as director of the Lowell Observatory,Slipher had the pleasure of announcing to theastronomical world that Tombaugh had discov-ered the planet Pluto.

But about three decades earlier, Slipher hadmade his own great contribution to astronomy atthe Lowell Observatory—a generally overlookeddiscovery that changed the trajectory of moderncosmology. Starting in about 1912, he used spec-troscopic measurements and exposure times aslong as 80 hours to measure the enormous radialvelocities of spiral nebulas. Slipher determinedthe radial velocities of these so-called spiral neb-ulas (now known to be galaxies beyond theMilky Way) by measuring the displacement oftheir spectral lines. The Doppler effect, for ex-ample, will shift spectral lines toward the red(longer wavelength) portion of the visible spec-trum if the object is going away (receding) fromEarth and toward the blue or violet portion ofthe spectrum if the object is approaching at highvelocity.

In 1913 Slipher examined the spectrallines from the great spiral nebula in Andromeda(also known as Messier catalogue number M31or the Andromeda Galaxy) and, to his surprise,discovered this object was approaching Earth(indicated by blueshifted spectral lines) at approximately 300 kilometers per second. Heextended this work to many other spiral nebulas and soon discovered that out of the 40he had carefully observed, 36 displayed red-

shifted spectral lines and only four blueshiftedspectral lines. Slipher also measured radial velocities in excess of many thousands of kilo-meters per second.

The mystery presented by these data puz-zled him and other astronomers includingHARLOW SHAPLEY. However, unable to resolvethe mystery astronomers preferred to simply ig-nore these important data, often suggestingthat Slipher’s experimental technique wasfaulty or his interpretation of the data in error.But one great astronomer did not ignore the in-credibly important implications of Slipher’swork. Hubble used Slipher’s work as a startingpoint to develop his cosmology of an expand-ing universe filled with millions of galaxies re-ceding from Earth. Hubble presented theseideas in the late 1920s and changed forever ourview of the vast size and dynamic nature of theuniverse.

As a very skilled astronomer, Slipher ap-plied spectroscopic techniques at the LowellObservatory to prove the existence of vast quan-tities of dust and gas in interstellar space and toinvestigate the atmospheric composition of thegaseous giant planets Jupiter, Saturn, Uranus,and Neptune. In the early 1930s he also inves-tigated the phenomenon of zodiacal light—thefaint cone of light extending upward fromEarth’s horizon in the direction of the eclipticcaused by the reflection of sunlight from tinypieces of interplanetary dust in orbit around theSun.

Numerous awards marked Slipher’s contri-butions to astronomy, including the LalandePrize and Gold Medal from the French Academyof Sciences (1919), the Henry Draper Medal ofthe National Academy of Sciences (1932), theGold Medal of the Royal Astronomical Society(1933), and the Bruce Gold Medal from theAstronomical Society of the Pacific (1935). Theastronomer whose pioneering spectroscopicstudies of spiral nebulas led to our modern un-derstanding of the expanding universe died in

Stefan, Josef 267

Flagstaff, Arizona, on November 8, 1969, justfour days short of his 94th birthday.

5 Stefan, Josef(1835–1893)AustrianPhysicist

In about 1879 Josef Stefan experimentallydemonstrated that the energy radiated per unittime by a blackbody was proportional to thefourth power of that body’s absolute temperature.When LUDWIG BOLTZMANN provided the theo-retical foundations for this relationship in 1884,the collaboration of the two Austrian physicistsresulted in the formulation of the famous Stefan-Boltzmann law—a physical principle of greatimportance to astronomers and astrophysicists.

Stefan was born on March 24, 1835, in St.Peter, near Klagenfurt, Austria. He received hischildhood education in Klagenfurt and then en-tered the University of Vienna to study physicsand mathematics. Upon graduation in 1858, hereceived an appointment as lecturer in mathe-matical physics at the university. By 1866 heearned the rank of professor of mathematics andphysics and also became the director of thePhysical Institute in Vienna. He stayed affiliatedwith the university for the remainder of his life.He was an excellent experimental physicist anda very well-liked instructor. One of his mostfamous students was Boltzmann.

As an experimental physicist, Stefan had awide range of research interests, including opti-cal interference, the kinetic theory of gases, elec-tromagnetic induction, diffusion, thermomag-netic phenomena, and the cooling rate of hotbodies. He is best remembered for his pioneeringwork with respect to radiation heat transfer.

Stefan carefully investigated thermal energy lossesfrom hot bodies, such as heated platinum wires,and he became the first scientist to effectivelyquantify the phenomenon of radiation heat trans-fer. In 1879 he noted that the rate of thermal en-ergy loss was proportional to the fourth power ofan object’s absolute temperature. For example, ifthe temperature of an object doubled, say from1,000 to 2,000 kelvins, the amount of thermal en-ergy it radiated increased 16-fold.

In 1884 one of his former students, Boltz-mann, provided the theoretical basis for Stefan’sempirical observations. Boltzmann used thermo-dynamic principles to develop the famous physi-cal law that is now called the Stefan-Boltzmannlaw. This law states that the luminosity, or radi-ant power, of a blackbody is proportional to thefourth power of the blackbody’s absolute temper-ature. Astronomers and astrophysicists often usethis law to describe and compare the radiantproperties and temperatures of stars, because to agood approximation stars closely approximatethe behavior of blackbody radiators. For conven-ience, astronomers will also frequently use theluminosity, radius, and absolute surface tempera-ture of the Sun as their reference and then applythe Stefan-Boltzmann law to form a ratio thatcompares the corresponding values for anotherstar to this solar baseline.

During his lifetime, Stefan was honoredwith special appointments, including those ofRector Magnificus at the University of Viennain 1876 and vice president of the VienneseAcademy of Sciences in 1885. He died onJanuary 7, 1893, in Vienna, Austria. His radia-tion heat transfer research provided a majorbreakthrough in the understanding of blackbodyradiation and set the stage for MAX KARL

PLANCK and his development of the quantumtheory of thermal radiation.

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T5 Tereshkova, Valentina

(1937– )RussianCosmonaut

The early race into space between the Sovietsand the Americans produced a win for theSoviets and for women in space explorationwhen Valentina Tereshkova became the firstwoman to fly into space on June 16, 1963.

From her humble beginnings in the Russianvillage of Masslenikovo, where she was born tofarmworkers on March 6, 1937, young Tereshkovacould easily have been considered least likely tobecome a world-renowned figure. At age 18, theyoung woman left school to work in a textile mill.In hindsight, one of the most important decisionsto her future career came when she joined a para-chutists’ club. Her first jump, at age 22, would dofar more than propel her from a plane. It would ultimately help launch her into the Russianspace program.

In 1961 Tereshkova decided to become acosmonaut. Her timing was good: Since Gher-man Titov had recently made a flight into space,the Russian government was contemplatingsomething new—sending a woman into space.

Fortunately for Tereshkova, they decided thatthis woman must be a parachutist.

One of only five women to be considered forthe role, Tereshkova was selected for the Vostok6 flight in May 1963 by Premier Khrushchevhimself, who was pushing the space race to beatout the United States with as many Soviet “firsts”as possible. The following month, she had herhistoric moment in space. The event lasted 70hours, 50 minutes, allowing Tereshkova to orbitthe Earth once every 88 minutes. Parachutingcame into play when, upon reentering the at-mosphere, she jumped from the spacecraft andlanded in central Asia.

While she never ventured into space again,Tereshkova played a pivotal role for women inastronomy as the first woman to physically enterthis new frontier. She has since received twoOrder of Lenin awards, as well as the UnitedNations Gold Meal of Peace, the SimbaInternational Women’s Movement Award, andthe Joliot-Curie Gold Medal.

5 Tombaugh, Clyde William(1906–1997)AmericanAstronomer

Tombaugh, Clyde William 269

Clyde Tombaugh was the “farm boy astronomer”who discovered the planet Pluto on February 18,1930. He did this while working as a juniorastronomer at the Lowell Observatory nearFlagstaff, Arizona. His success came throughvery hard work, perseverance, and Tombaugh’sskilled use of the “blinking comparator”—aninnovative approach to astrophotography basedon the difference in photographic images takena few days apart. His discovery of the elusivetrans-Neptunian planet also helped fulfill thedreams of the observatory’s founder, PERCIVAL

LOWELL, who had predicted the existence of a“Planet X” decades earlier.

Clyde Tombaugh was born on February 4,1906, on a farm near Streator, Illinois. Whenhe was in secondary school, his family movedto the small farming community of Burdett inthe western portion of Kansas. When Tombaughgraduated from Burdett High School in 1925,he had to abandon any immediate hope of at-tending college, because crop failures had re-cently impoverished his family. While growingup on the farm, he acquired a very strong in-terest in amateur astronomy from his father. Tocomplement this interest, he taught himselfmathematics and physics. In 1927 he con-structed several homemade telescopes, includ-ing a 9-inch reflector built from discarded farmmachinery, auto parts, and handmade lenses andmirrors. Using this reflector telescope under thedark skies of western Kansas, he spent eveningsobserving and made detailed drawings of Marsand Jupiter. Searching for advice and commentsabout his observations, Tombaugh submitted hisdrawings in 1928 to the professional planetaryastronomers at the Lowell Observatory inFlagstaff, Arizona. To his great surprise, the as-tronomers were very impressed with his detaileddrawings, which revealed his great talent as acareful and skilled astronomical observer.

So despite the fact that Tombaugh lacked aformal education in astronomy, VESTO MELVIN

SLIPHER, the director of the Lowell Observatory,hired him in 1929 as a junior astronomer. Slipheralso placed Tombaugh on a rendezvous trajectorywith astronomical history when he assigned theyoung “farm boy astronomer” to the monumen-tal task of searching the night sky for Planet X.As early as 1905, Lowell had noticed subtle per-turbations in the orbits of Neptune and Uranus,which he attributed to the gravitational tug ofsome undetected planet farther out in the solarsystem. After several more years of investigation,Lowell boldly predicted in 1915 the existence ofthis “Planet X” and began to conduct a detailedphotographic search in candidate sections of thesky from his newly built observatory in Flagstaff.Unfortunately, Lowell died in 1916 without find-ing his mysterious Planet X.

Using a 13-inch photographic telescope atthe Lowell Observatory, Tombaugh embarked ona systematic search for the planet. He workedthrough the nights in a cold, unheated dome,making pairs of exposures of portions of the skywith time intervals of two to six days. He thencarefully examined these astrographs (star pho-tographs) under a special device called the blink-comparator in the hope of detecting the smallshift in position of one faint point of light amonghundreds of thousands of points of light—thesign of Planet X among a field of stars. On thenights of January 23 and 29, 1930, Tombaughmade two such photographs of the region of thesky near the star Delta Geminorum. On the af-ternoon of February 18, 1930, he triumphed.While viewing these photographic plates underthe blink-comparator, Tombaugh detected thetelltale shift of a faint starlike object. Slipher andother astronomers at the observatory verified theresults and rejoiced in Tombaugh’s discovery.However, caution was urged and time was takenfor Tombaugh to confirm this important discov-ery. The discovery of Pluto was confirmed withsubsequent photographic measurements and an-nounced to the world on March 13, 1930.

270 Tombaugh, Clyde William

With the announcement of this discovery,Tombaugh joined an exclusive group of as-tronomers who observed and then named majorplanets in the solar system. Of the many thou-sands of astronomers in history who havesearched the heavens with telescopes, only thefollowing accompany Tombaugh in this very elitegroup—SIR WILLIAM HERSCHEL, who discoveredUranus in 1781, and JOHANN GOTTFRIED GALLE,who discovered Neptune in 1846 (credit for thisdiscovery is shared by JOHN COUCH ADAMS andURBAIN-JEAN-JOSEPH LEVERRIER). In keeping withastronomical tradition, Tombaugh had the rightas the planet’s discoverer to give the distant ce-lestial body a name. He chose Pluto, god of dark-ness and the underworld in Roman mythology.

Pluto is a tiny, frigid world, very different fromthe gaseous giant planets that occupy the outersolar system. For that reason there is some debatewithin the astronomical community as towhether Pluto is really a “major planet” or per-haps should be regarded as an icy moon that es-caped from Neptune or perhaps a large Kuiperbelt object. As more and more trans-Neptunianobjects are discovered beyond the orbit of Pluto,this debate will most likely intensify in the 21stcentury. But for now, Pluto is regarded as theninth major planetary body in the solar systemand Tombaugh’s discovery represents a marvelousaccomplishment in 20th-century observationalastronomy.

After discovering Pluto, Tombaugh remainedwith the Lowell Observatory for the next 13 years.During this period, he also entered the Universityof Kansas on scholarship in 1932 to pursue theundergraduate education he had been forced todelay because of financial constraints. In 1934,while attending the university, he met and mar-ried Patricia Edson of Kansas City. The couple re-mained married for more than 60 years and raisedtwo children. While observing during the sum-mers at the Lowell Observatory, Tombaughearned his bachelor of science degree in astron-omy in 1936 and then his master of arts degree

in astronomy in 1939. He frequently told the storyof his perplexed astronomy professor who did notwant a “planet discoverer” in his basic astronomycourse.

Upon graduation, he returned to the LowellObservatory and continued a rigorous program ofsky watching that resulted in his meticulous cat-aloging of more than 30,000 celestial objects, in-cluding hundreds of variable stars, thousands ofnew asteroids, and two comets. He also engagedin a search for possible small natural satellites en-circling Earth. However, save for the Moon, hecould not find any natural satellites of Earth thatwere large enough or bright enough to be detectedby means of photography.

During World War II, Tombaugh taught nav-igation to military personnel from 1943 to 1945at Arizona State College (now called NorthernArizona University). Following World War II, theLowell Observatory did not rehire him as an as-tronomer, because of funding reductions. InsteadTombaugh went to work for the military at theWhite Sands Missile Range, in Las Cruces, NewMexico. There he supervised the developmentand installation of the optical instrumentationused during the testing of ballistic missiles, in-cluding WERNHER VON BRAUN’s V-2 rockets thathad been captured in Germany by the U.S. Armyat the close of the war.

Tombaugh left his position at the WhiteSands Missile Range in 1955 and joined the fac-ulty at New Mexico State University in LasCruces. He helped this university establish a plan-etary astronomy program and remained an activeobservational astronomer. Upon retirement fromthe university in 1973, he went on extensive lec-ture tours throughout the United States andCanada, accompanied by his wife, to raise moneyfor scholarships in astronomy at New MexicoState University. Several weeks before his 91stbirthday, Tombaugh died on January 17, 1997, inLas Cruces.

Tombaugh was recognized around the worldas the discoverer of Pluto, and the only American

Tsiolkovsky, Konstantin Eduardovich 271

to discover a planet. He became a professor emer-itus in 1973 at New Mexico State University andpublished several books, including The Search forSmall Natural Earth Satellites (1959) and Out of theDarkness: The Planet Pluto (1980), coauthoredwith Patrick Moore.

5 Tsiolkovsky, Konstantin Eduardovich(1857–1935)RussianPhysicist, (Theoretical) Rocket Engineer

The nearly deaf Russian schoolteacherKonstantin Eduardovich Tsiolkovsky was a theo-retical rocket expert and space travel pioneerlight-years ahead of his time. At the beginning ofthe 20th century, Tsiolkovsky worked independ-ent of ROBERT HUTCHINGS GODDARD andHERMANN JULIUS OBERTH, toward their commonvision: the use of rockets for interplanetary travel.This brilliant schoolteacher lived a simple life inisolated, rural towns in czarist Russia. Yet he wrotewith such uncanny accuracy about modern rock-ets and space that he cofounded astronautics.Primarily a theorist, Tsiolkovsky never con-structed any of the rockets he proposed in his re-markably prophetic books but they inspired manyfuture Russian cosmonauts, space scientists, androcket engineers, including SERGEI PAVLOVICH

KOROLEV, whose powerful rockets helped fulfillTsiolkovsky’s predictions.

Tsiolkovsky was born on September 17,1857, in the village of Izhevskoye, in the RyazanProvince of Russia. His father, EduardIgnatyevich Tsiolkovsky, was a Polish noble bybirth, but now in exile working as a provincialforestry official. His mother, Mariya YumashevaTsiolkovskaya was Russian and Tartar. At agenine a near-fatal attack of scarlet fever left himalmost totally deaf. With his loss of hearing, headjusted to a lonely, isolated childhood in whichbooks became his friends. He also learned to ed-ucate himself and in the process acquired a highdegree of self-reliance.

At age 16 Tsiolkovsky ventured to Moscow,where he studied mathematics, astronomy, me-chanics, and physics. He used an ear trumpet tolisten to lectures and struggled with a meager al-lowance of just a few kopecks (pennies) eachweek for food. Three years later Tsiolkovsky re-turned home. He soon passed the schoolteacher’sexamination and began his teaching career at arural school in Borovsk, located about 100 kilo-meters from Moscow. In Borovsk he met and mar-ried his wife, Varvara Sokolovaya. He remaineda provincial schoolteacher in Borovsk for morethan a decade. Then, in 1892, Tsiolkovsky movedto another teaching post in Kaluga, where he re-mained until he retired in 1920.

As he began his teaching career in ruralRussia, Tsiolkovsky also turned his fertile mind toscience, especially concepts about rockets andspace travel. Despite his severe hearing impair-ment, Tsiolkovsky’s tenacity and self-reliance al-lowed him to become an effective teacher andalso to make significant contributions to the fieldsof aeronautics and astronautics.

But teaching in rural Russian villages in thelate 19th century physically isolated Tsiolkovskyfrom the mainstream of scientific activities, bothin his native country and elsewhere in the world.He independently worked out the kinetic theoryof gases in 1881, then proudly submitted a manu-script concerning this original effort to the Russ-ian Physico-Chemical Society. Unfortunately forTsiolkovsky, the famous chemist DmitriMendeleyev (1834–1907) informed him that thetheory had been developed a decade earlier. How-ever, the originality and quality of Tsiolkovsky’spaper impressed Mendeleyev and the otherreviewers, and they invited him to become amember of the society.

While teaching in Borovsk, Tsiolkovskyused his own meager funds to construct the firstwind tunnel in Russia. He did this so he couldexperiment with airflow over various stream-lined bodies. He also began making models ofgas-filled, metal-skinned dirigibles. His interest

272 Tsiolkovsky, Konstantin Eduardovich

in aeronautics served as a stimulus for his morevisionary work involving the theory of rocketsand their role in space travel. As early as 1883,he accurately described the weightlessness con-dition of space in an article entitled “FreeSpace.” In his 1895 book, Dreams of Earth andSky, Tsiolkovsky discussed the concept of an ar-tificial satellite orbiting Earth. By 1898 he cor-rectly linked the rocket to space travel and con-cluded that it would have to be a liquid-fueledrocket to achieve the necessary escape velocity.The escape velocity is the minimum velocity anobject must acquire in order to overcome thegravitational attraction of a large celestial body,such as planet Earth. To completely escape fromEarth’s gravity, for example, a spacecraft wouldneed to reach a minimum velocity of approxi-mately 11 kilometers per second.

Many of the fundamental principles of astro-nautics were described in his seminal work,Exploration of Space by Reactive Devices. This im-portant theoretical treatise showed that spacetravel was possible using the rocket. Another pi-oneering concept found in the book is a designfor a liquid-propellant rocket that used liquid hy-drogen and liquid oxygen. Tsiolkovsky delayedpublishing the important document until 1903.One possible reason for the delay is the fact thatTsiolkovsky’s son, Iganty, had committed suicidein 1902.

Because of Tsiolkovsky isolation his impor-tant work in aeronautics and astronautics wentessentially unnoticed by the world. Few in Russiacared about space travel in those days and henever received significant government funding topursue any type of practical demonstration of hisinnovative concepts. His suggestions included thespace suit, space stations, multistage rockets, large

habitats in space, the use of solar energy, andclosed life support systems.

In the first two decades of the 20th century,things seemed to go from bad to worse inTsiolkovsky’s life. In 1908 an overflowing riverflooded his home and destroyed many of his notesand scientific materials. Undaunted, he salvagedwhat he could, rebuilt, and pressed on with teach-ing and writing about space.

Following the Russian Revolution of 1917,the new Soviet government grew interested inrocketry and rediscovered Tsiolkovsky’s amazingwork, honoring him for his previous achieve-ments in aeronautics and astronautics andencouraging him to continue his pioneeringresearch. He received membership in the SovietAcademy of Sciences in 1919, and the govern-ment granted him a pension for life in 1921 inrecognition of his teaching and scientific contri-butions. Tsiolkovsky used the free time ofretirement to continue to make significant con-tributions to astronautics. In 1924 he publishedhis book Cosmic Rocket Trains, in which he rec-ognized that a single-stage rocket would not bepowerful enough to escape Earth’s gravity on itsown, so he developed the concept of a stagedrocket, which he called a rocket train. Tsi-olkovsky’s visionary writings inspired manyfuture cosmonauts and aerospace engineers,including Korolev.

Tsiolkovsky died in Kaluga on September 19,1935. His epitaph conveys the important message“Mankind will not remain tied to Earth forever.”As part of the Soviet Union’s centennial cele-bration of Tsiolkovsky’s birth, one of Korolev’s en-visioned powerful rockets launched Sputnik 1, theworld’s first artificial satellite—starting the SpaceAge on October 4, 1957.

U

273

5 Urey, Harold Clayton(1893–1981)AmericanChemist, Exobiologist

Harold Urey was the American physical chemistwho won the 1934 Nobel Prize in chemistry forhis discovery of the hydrogen isotope deuterium.In World War II he contributed to uranium iso-topic enrichment efforts as part of the U.S.atomic bomb program known as the ManhattanProject. Then, starting in the early 1950s, hemade a very exciting contribution to the emerg-ing field of planetary sciences by conductingone of the first experiments in exobiology—aclassic experiment often known as the Urey-Miller experiment.

He was born on April 29, 1893, in Walkerton,Indiana, the son of a minister and the grandsonof one of the pioneers who originally settled thearea. Following his early education in ruralschools and high school graduation in 1911,Urey taught for three years in country schools.Then, in 1914, he enrolled in the University ofMontana and earned his bachelor of science de-gree in zoology in 1917. He spent the next twoyears as an industrial research chemist and thenreturned to Montana to teach chemistry. In1921 he entered the University of Californiaand graduated in 1923 with a Ph.D. in chemistry.

With funding from an American-ScandinavianFoundation fellowship, Urey traveled to Denmark,where he spent a year in postdoctoral researchat Niels Bohr’s Institute of Theoretical Physics.Upon his return to the United States, he becamean associate professor in chemistry at JohnsHopkins University.

In 1929 Urey accepted an appointment asan associate professor in chemistry at ColumbiaUniversity. There, in 1931, while engaging in re-search on diatomic gases, he devised a method toconcentrate any possible heavy hydrogen isotopesby the fractional distillation of liquid hydrogen.His efforts led to the discovery of deuterium (D),the nonradioactive heavy isotope of hydrogenthat forms heavy water (D2O). He became a fullprofessor at Columbia in 1934. From 1940 to 1945Urey also served as the director of War Research,Atomic Bomb Project, at Columbia University.After World War II he moved to the Universityof Chicago and served there as a distinguishedprofessor of chemistry until 1955.

While at the University of Chicago in theearly 1950s, he made a dramatic break away fromhis previous Nobel Prize–winning efforts in ter-restrial chemistry and began to investigate thepossible origins of life on Earth and elsewhere inthe universe from the perspective of extraterres-trial chemistry. As one of the first exobiologists,he introduced some of the basic ideas in this field

274 Urey, Harold Clayton

with his 1952 book The Planets: Their Origin andDevelopment. In 1953, together with his gradu-ate student Stanley Miller (b. 1930), Urey per-formed the famous exobiology experiment thatis now widely known as the “Urey-Miller ex-periment.” They created gaseous mixtures, sim-

ulating Earth’s primitive atmosphere, and thensubjected these mixtures to various energysources, such as ultraviolet radiation and light-ning discharges. Within days, life-precursor or-ganic compounds known as amino acids beganto form in some of the test beakers.

The American chemist and Nobel laureate Harold Urey at work in his laboratory. Early in his career, Ureydiscovered the nonradioactive isotope of ordinary hydrogen called deuterium. He received the 1934 Nobel Prizein chemistry for this accomplishment. Later in his career, he became one of the earliest exobiologists as heinvestigated the origins of life on Earth and the possibility of life in other worlds. In 1953, together with hisstudent Stanley Miller, Urey performed the classic exobiology experiment in which gaseous mixtures thatsimulated Earth’s primitive atmosphere were subjected to various energy sources. To their pleasant surprise, life-forming organic compounds (amino acids) appeared in the solutions. (Argonne National Laboratory, courtesy AIPEmilio Segrè Visual Archives)

Urey, Harold Clayton 275

The intriguing question that other scien-tists began to seriously ask after the Urey-Millerexperiment was: “If life started in a primordialchemical soup here on Earth, does (or can) lifestart on other worlds that have similar primi-tive environments?” The question of whetherlife is unique to Earth or common throughoutthe Galaxy remains unanswered in the 21stcentury.

In 1958 Urey accepted a position at theUniversity of California in La Jolla, and he re-mained with that institution until he retired in1970. He died on January 5, 1981, in La Jolla.

The 1934 Nobel Prize in chemistry highlightedhis achievements as a terrestrial chemist, but hisinnovative work in extraterrestrial chemistrymay have far greater technical consequences.Thanks to Urey’s supervision of pioneering ex-periments at the University of Chicago, exobiol-ogy has become a credible part of contemporaryspace science programs—most notably reflectedtoday by NASA’s continued search for micro-scopic life on Mars and the space organization’splanned search for possible alien life in the sus-pected subsurface liquid water ocean on theJovian moon Europa.

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V5 Van Allen, James Alfred

(1914– )AmericanPhysicist, Space Scientist

The pioneering space scientist James Van Allenplaced the Iowa cosmic ray experiment on thefirst U.S satellite, Explorer 1, and with this in-strument discovered the inner portion ofEarth’s trapped radiation belts in early 1958.Today, space scientists call this distinctivezone of magnetically trapped atomic particlesaround Earth the Van Allen radiation belts inhis honor.

Van Allen was born in Mount Pleasant, Iowa,on September 7, 1914. During his sophomore yearat Iowa Wesleyan College, he made his first meas-urements of cosmic ray intensities. After gradua-tion in 1935, he attended the University of Iowa,where he earned his master’s degree in 1936 andcompleted his doctoral degree in physics in 1939.From 1939 to 1942 Van Allen worked at theCarnegie Institution of Washington as a physicsresearch fellow in the department of terrestrialmagnetism. As a Carnegie Fellow, he receivedvaluable cross-training in geomagnetism, cosmicrays, nuclear physics, solar-terrestrial physics, andionospheric physics. All of this scientific cross-training prepared him well for his leading role as

the premier U.S. space scientist at the beginningof the Space Age.

In 1942 Van Allen transferred to the AppliedPhysics Laboratory at Johns Hopkins Universityto work on rugged vacuum tubes. He received awartime commission that autumn in the U.S.Navy, and served as ordnance specialist for the re-mainder of World War II. One of his primary con-tributions was the development of an effectiveradio proximity fuse—one that detonated an ex-plosive shell when the ordnance came near itstarget. Following combat duty in the Pacific, hereturned to the laboratory at Johns HopkinsUniversity in Maryland. One afternoon in March1945, he quite literally ran into his future wife,Abigail, during a minor traffic accident. Sixmonths later both drivers were married and theirfortuitous traffic encounter eventually yielded fivechildren and a house full of grandchildren.

In the postwar research environment, VanAllen began applying his wartime engineeringexperience to miniaturize the rugged new elec-tronic equipment. He used this small, but tough,equipment in conjunction with his pioneeringrocket and satellite scientific instrument pay-loads. By spring 1946 the navy transferredLieutenant Commander Van Allen to its inac-tive reserve and he resumed his war-interruptedresearch work at Johns Hopkins. He remained

Van Allen, James Alfred 277

at the Applied Physics Laboratory until 1950,when he returned to the University of Iowa ashead of the physics department.

While at Johns Hopkins, Van Allen per-formed a series of preliminary space science ex-periments that anticipated his great discovery atthe dawn of the U.S. space program. He designedand constructed rugged, miniaturized instru-ments to collect geophysical data at the edge ofspace, using rides on captured German V-2 rock-ets, Aerobee sounding rockets, and even rocketslaunched from high altitude balloons (rock-oons). One of his prime interests was the meas-urement of the intensity of cosmic rays and anyother energetic particles arriving at the top ofEarth’s atmosphere from outer space. He carriedthese research interests back to the Universityof Iowa and over the years established an inter-nationally recognized space physics program.

On October 4, 1957, the Soviet Unionshocked the world by sending the first artificialsatellite, Sputnik 1, into orbit around Earth. Inaddition to starting the Space Age, this satelliteforced the United States into a hotly contestedspace technology race. In a desperate attemptto win the race, both the Soviets and theAmericans started pumping large quantities ofmoney into the construction of military andscientific (civilian) space systems.

Fortune often favors the prepared. As agifted scientist, Van Allen was well prepared forthe great opportunity that suddenly came hisway. With the dramatic failure of the firstVanguard rocket vehicle at Cape Canaveral,Florida, in early December 1957, senior U.S.government officials made an emergency deci-sion to launch the country’s first satellite with amilitary rocket. A scientific payload that wasrugged enough to fly on a rocket was needed atonce. Van Allen’s Iowa cosmic-ray experimentwas available and quickly selected to become theprincipal component of the payload on Explorer1. He responded to this great opportunity by

providing a rugged Geiger-Muller tube to the JetPropulsion Laboratory, which was on contractwith the U.S. Army to construct the upper stage-spacecraft portion of Explorer 1. Van Allen’sscientific instrument was sturdy enough tosurvive the ride into space on a rocket and thenstart collecting interesting geophysical datathat was transmitted back to Earth by the hostspacecraft.

All was ready on January 31, 1958. The U.S.Army hastily pressed a Jupiter C rocket intoservice as a launch vehicle, with a cleverly im-provised configuration designed by WERNHER

MAGNUS VON BRAUN. Flawlessly, the rocketrumbled into orbit from Cape Canaveral,Florida. Soon the first U.S. satellite, Explorer 1,traveled in orbit around Earth. As the satelliteglided though space, Van Allen’s ionizing radi-ation detector, primarily designed to measurecosmic ray intensity, jumped off scale. As a greatsurprise to Van Allen and other scientists, thisinstrument had unexpectedly detected the innerportion of Earth’s trapped radiation belts.

The Explorer II spacecraft, launched intoorbit on March 26, 1958, carried an augmentedversion of Van Allen’s Iowa cosmic-ray instru-ment. That spacecraft harvested an enormousquantity of data about the radiation environ-ment in space and confirmed the presence oftrapped energetic charged-particle belts (mainlyelectrons and protons) within Earth’s magne-tosphere. These belts are now called the VanAllen radiation belts. Soon an armada of space-craft poked and probed the region of outer spacenear Earth, defining the extent, shape, and com-position of Earth’s trapped radiation belts. VanAllen became an instant scientific celebrity.Because of his widely recognized space scienceaccomplishments, he has since met eight U.S.presidents.

In the 1960s and 1970s he assisted theNational Aeronautics and Space Adminis-tration in planning, designing, and operating

energetic particle instruments on planetary ex-ploration spacecraft to Mars, Venus, Jupiter, andSaturn. Since Explorer 1, Van Allen and histeam of researchers and graduate students at theUniversity of Iowa have actively participatedin many other pioneering space exploration

missions. Members of this group have publishedmajor papers dealing with Jupiter’s intenselypowerful magnetosphere, the discovery and pre-liminary survey of Saturn’s magnetosphere, andthe energetic particles population in interplan-etary space.

278 Van Allen, James Alfred

Pioneering space scientist James Van Allen was part of the jubilant team that launched the first American satellite,Explorer I, on January 31, 1958. Appearing in this photograph are: (left) William H. Pickering, former director ofthe Jet Propulsion Laboratory, which built and operated the satellite; (center) James Van Allen, who designed andbuilt the satellite’s space science instruments; and (right) Wernher von Braun, who built the launch vehicle thatsuccessfully sent the satellite into orbit around Earth. They are holding a model of Explorer I, whose instrumentsmade scientific history by detecting Earth’s trapped radiation belts—now called the Van Allen belts. (NASA)

Van Allen retired from the department ofphysics and astronomy at the University of Iowain 1985. However, as the Carver Professor ofPhysics Emeritus, he still pores over interestingspace physics data in his office in the campus

building appropriately named Van Allen Hall.His space physics efforts not only thrust theUniversity of Iowa into international promi-nence but he also served his nation as a truly in-spirational scientific hero.

Van Allen, James Alfred 279

280

W5 Wilson, Robert Woodrow

(1936– )AmericanPhysicist, Radio Astronomer

Robert Wilson collaborated with ARNO ALLEN

PENZIAS at Bell Laboratories in the mid-1960sand made the most important discovery in 20th-century cosmology. By detecting cosmic mi-crowave background radiation, they providedthe first empirical evidence in support of the BigBang theory presented as a doctoral thesis in1948 by RALPH ASHER ALPHER.

Robert Woodrow Wilson was born inHouston, Texas, on January 10, 1936. His child-hood visits to the company shop with his father,a chemist working for the oil industry, providedWilson with his lifelong interest in electronicsand machinery. In 1957 he received his bache-lor of arts degree with honors in physics fromRice University in Houston and then enrolledfor graduate work in physics at the CaliforniaInstitute of Technology (Caltech). At the timeWilson was not decided about what area ofphysics he wanted to pursue for his doctoral re-search. However, fortuitous meetings and dis-cussions on campus led him to become involvedin interesting work at Caltech’s Owens ValleyRadio Observatory—then undergoing develop-ment in the Sierra Nevada near Bishop,

California, and today the largest university-operated radio observatory in the world. ForWilson, graduate research in radio astronomyprovided a nice mixture of electronics andphysics. His decision to pursue this area of re-search placed him on a highly productive careerpath in radio astronomy. However, in 1958 hebriefly delayed his entry into radio astronomy toreturn to Houston so he could court and marryhis wife, Elizabeth Rhoads Sawin.

In 1959 Wilson took his first astronomycourses at Caltech and began working at theOwens Valley Radio Observatory during breaksin the academic calendar. He completed the lastpart of his thesis research under the supervisionof MAARTEN SCHMIDT, who was exploringquasars at the time. Following graduation withhis doctoral degree, Wilson stayed on at Caltechas a postdoctoral researcher and completed sev-eral other projects. In 1963 he joined BellLaboratories and soon met Penzias, the onlyother radio astronomer at the laboratory.

Between 1963 and 1965 the two collabo-rated in applying a special antenna six metersin diameter to investigate the problem ofradio noise from the sky. At this time, BellLaboratories had a general interest in detectingand resolving any cosmic radio noise problemsthat might adversely affect the operation of theearly communication satellites. Expecting radio

Wolf, Maximilian 281

noise to be less severe at shorter wavelengths,Wilson and Penzias were surprised to discoverthat the sky was uniformly “bright” at 7.3 cen-timeters wavelength in the microwave region.Discussions with Robert Dicke (1916–97) inspring 1965 indicated that Wilson and Penziashad stumbled upon the first direct evidence ofthe cosmic microwave background—the “HolyGrail” of Big Bang cosmology. Wilson andPenzias estimated the detected cosmic “radionoise” to be about three kelvins. Measurementsperformed by NASA’s Cosmic BackgroundExplorer (COBE) spacecraft between 1989 and1990 indicated that the cosmic microwavebackground closely approximates a blackbodyradiator at a temperature of 2.735 kelvins. Forthis great (though serendipitous) discovery,Wilson shared one half of the 1978 Nobel Prizein physics with Penzias. The other half of theaward that year went to the Russian physicistPyotr Kapitsa for unrelated work in low-temperature physics.

In the late 1960s and early 1970s, Wilsonand Penzias used techniques in radio astron-omy at millimeter wavelengths to investigatemolecular species in interstellar space. Theywere excited to unexpectedly find large quan-tities of carbon monoxide (CO) behind theOrion Nebula, and soon found that this mol-ecule was rather widely distributed throughoutthe Galaxy.

From 1976 to 1990 Wilson served as thehead of the Radio Physics Research Departmentat Bell Laboratories. He was elected to the U. S.National Academy of Sciences in 1979. In ad-dition to the 1978 Nobel Prize, Wilson also re-ceived the Herschel Medal from the RoyalAstronomical Society (1977) and the HenryDraper Medal from the American NationalAcademy of Sciences (1977). Wilson’s majorcontribution to astronomy was his codiscoveryof the cosmic microwave background—the lin-gering remnant of the Big Bang explosion thatstarted the universe.

5 Wolf, Maximilian (Max Wolf)(1863–1932)GermanAstronomer

Max Wolf was an asteroid hunter who pioneeredthe use of astrophotography to help him in hissearch for these elusive solar system bodies. Hediscovered more than 200 minor planets, in-cluding asteroid Achilles in 1906—the first ofthe Trojan group of asteroids. This group of mi-nor planets moves around the Sun in Jupiter’sorbit, but at the Lagrangian libration points of60 degrees ahead and 60 degrees behind thegiant planet.

Wolf was born on June 21, 1863, inHeidelberg, Germany, the city where he spentalmost his entire lifetime. His father was a re-spected physician and the family was comfort-ably wealthy. When Wolf was a young boy, hisfather encouraged him to develop an interest inscience and astronomy by building him a privateobservatory adjacent to the family’s residence.His father’s investment was a good one. Wolfcompleted his doctoral degree in mathematicalstudies at the University of Heidelberg in 1888and then went to the University of Stockholmfor two years of postdoctoral work. He returnedto Heidelberg in 1890 and began lecturing in as-tronomy at the university as a Privatdozent (un-paid instructor). In 1893 Wolf received a dualappointment from the University of Heidelbergto serve as a special professor of astrophysicsand to direct the new observatory being con-structed at nearby Königsstuhl. In 1902 he be-came the chair of astronomy at the universityand, along with his directorship of the KönigsstuhlObservatory, remained in these positions untilhis death.

Wolf performed important spectroscopicwork concerning nebulas and published 16 listsof nebulae containing a total of about 6,000 ce-lestial objects. But he is best remembered as be-ing the first astronomer to use photography to

282 Wolf, Maximilian

find asteroids. In 1891 he demonstrated the abil-ity to photograph a large region of the sky witha telescope that followed the “fixed” stars pre-cisely as the Earth rotated. The stars thereforeappeared as points, while the minor planets hehunted appeared as short streaks on the photo-graphic plate. On September 11, 1898, he dis-covered his first asteroid with this photographictechnique and named the celestial object Brucia(also called asteroid 323) to honor the Americanphilanthropist Catherine Wolfe Bruce. She haddonated money for Wolf’s new telescope at theKönigsstuhl Observatory. She also establishedthe Bruce Gold Medal as the award presentedannually to an astronomer in commemorationof his or her lifetime achievements.

By the end of 1898, Wolf had discoverednine other minor planets using astrophotogra-phy. Over the next three decades, this techniqueallowed him to personally discover more than

200 new asteroids, including asteroid 588, Achilles.Wolf found and named Achilles in 1906, notingthat it orbited the Sun at the L4 Lagrangianpoint 60 degrees ahead of Jupiter. The Trojangroup is the collection of minor planets found atthe two Lagrangian libration points lying onJupiter’s orbital path around the Sun. The namecomes from the fact that many of these asteroidswere named after the mythical heroes of theTrojan War.

Wolf was an avid asteroid hunter and a pi-oneer in astrophotography. In recognition of hiscontributions to astronomy, he received theGold Medal of the Royal Astronomical Societyin 1914 and the Bruce Gold Medal from theAstronomical Society of the Pacific in 1930.He held membership in both the AmericanAstronomical Society and the Royal Astro-nomical Society of Great Britain. He died inHeidelberg on October 3, 1932.

Z

283

5 Zwicky, Fritz(1898–1974)SwissAstrophysicist

Shortly after EDWIN POWELL HUBBLE introducedthe concept of an expanding universe in the late1920s, Fritz Zwicky pioneered the early search forthe “dark matter” (that is, the missing mass) ofthe universe. While collaborating with WILHELM

HEINRICH WALTER BAADE in 1934, he coined theterm supernova to describe certain very cata-clysmic nova phenomena. Zwicky, a visionarywith an extremely eccentric and often caustic per-sonality, also postulated that the by-product ofthis supernova explosion would be a neutron star.

Fritz Zwicky was born on February 14, 1898,in Varna, Bulgaria. A lifelong Swiss citizen, hespent his childhood in Mollis, a village in theCanton (state) of Glarus, Switzerland. He re-ceived his education in physics at the FederalInstitute of Technology in Zürich, graduatingwith a Ph.D. in 1922. While a graduate student,Zwicky interacted with the Swiss physicistAuguste Piccard (1884–1962) and performed hisdissertation research under a Nobel laureate, theDutch-American physical chemist Peter Deybe(1884–1966).

Since ALBERT EINSTEIN was a physics in-structor at the Federal Institute in Zurich when

Zwicky was also enrolled there as a student,science historians often suggest that he was astudent of Einstein. Without question, Zwickywas a very creative and intelligent physicist, sohe could certainly have engaged in interestingscientific discussions with Einstein, as both a stu-dent in Switzerland and then after graduation,when he became a professor at the CaliforniaInstitute of Technology (Caltech). However, thetruth is not known. What is clear is that Zwickyhad a dark side to his technical genius. He wasvery abrasive and fond of using rough languageand intimidating colleagues and students alike.Only a few extremely tolerant individuals, suchas Baade, could or would overlook his eccentricand difficult personality in order to encounterthe bursts of genius that occasionally could befound within Zwicky’s characteristically causticcomments.

At the invitation of the Nobel laureatephysicist Robert Millikan (1868–1953), Zwickycame to the United States in 1925 to work asa postdoctoral fellow at Caltech. Claiming heenjoyed the mountains near Pasadena, Zwickyremained affiliated with that institution andstayed in California for the rest of his life.However, despite living and working for almostfive decades in the United States, Zwicky re-tained his Swiss citizenship and never chose toapply for U.S. citizenship.

284 Zwicky, Fritz

In 1927 he became a professor of theoreti-cal physics and retained that academic positionat Caltech until he became a professor of astro-physics there in 1942. He retired from Caltechin 1972 given the status of professor emeritus inrecognition of his lifelong service to the univer-sity and to astrophysics. While at CaltechZwicky interacted with many of the world’s bestastronomers, including Baade, who came toSouthern California to use the Mount WilsonObservatory, located in the nearby San GabrielMountains. On campus at Caltech, Zwicky’s

antics are legendary. When encountering anunfamiliar student on campus, Zwicky wouldoften suddenly stop, stare in his or her face,and loudly inquire: “Who the hell are you?”Similarly, during a lecture on campus, he mightsuddenly stand up and leave the room, pausingat the door to turn around and inform the star-tled speaker that he (Zwicky) had alreadysolved the particular problem under discus-sion. Without question, many on the campusbreathed a sigh of relief when Zwicky commit-ted much of his time between 1943 and 1946to direct research at the Aerojet Corporation inAzusa, California, in support of jet engine de-velopment and other defense-related activities.

Despite his extensive involvement with as-tronomers, many of them also fell victim to hisaggressive social behavior. While working at theMount Wilson Observatory or at the PalomarObservatory, Zwicky would often inject one ofhis favorite exclamations, that all astronomerswere “spherical bastards.” Why spherical? Well,according to Zwicky, astronomers “looked thesame when viewed from any direction.” But be-hind this difficult personality was a gifted astro-physicist who helped establish the framework ofmodern cosmology.

In 1933, while investigating the ComaCluster—a rich cluster of galaxies in theConstellation Coma Berenices (also known asBerenice’s Hair)—Zwicky observed that the ve-locities of the individual galaxies in this clus-ter were so high that they should definitelyhave escaped from each other’s gravitationalattraction long ago. Zwicky, never afraid ofcontroversy, quickly came to the pioneeringconclusion that the amount of matter actuallyin that cluster had to be much greater thanwhat could be accounted for by the visiblegalaxies alone—an amount estimated to beonly about 10 percent of the mass needed togravitationally bind the galaxies in the cluster.Zwicky then focused a great deal of his atten-tion on the problem of this “missing mass” or,

The Swiss astrophysicist Fritz Zwicky lecturing at theCalifornia Institute of Technology (Caltech). In the late1920s he pioneered the early search for the “darkmatter” (that is, the missing mass) of the universe.While collaborating with Walter Baade in 1934, hecoined the term supernova to describe certain verycataclysmic nova phenomena. Zwicky, a visionarywith an extremely eccentric and often causticpersonality, also postulated that the by-product ofthis supernova explosion would be a neutron star.(AIP Emilio Segrè Visual Archives)

Zwicky, Fritz 285

as it is now more commonly called, the prob-lem of “dark matter.”

To support his research in dark matter,Zwicky and his collaborators started to use the18-inch Schmidt telescope at the PalomarObservatory near San Diego in 1936 to investi-gate and then catalog numerous clusters ofgalaxies. Between 1961 and 1968 Zwicky pub-lished the results of this intense effort as a six-volume work called Catalog of Galaxies and ofClusters of Galaxies. Sometimes simply referredto as the Zwicky catalog, this important workcontained about 10,000 clusters (classified aseither compact, medium compact, or open) andapproximately 31,000 galaxies.

While investigating bright novas withBaade in 1934, Zwicky coined the term super-nova to describe the family or new class of no-vas that appeared to be far more energetic andcataclysmic than any of the more frequentlyencountered novas. The classical nova phe-nomenon involves a sudden and unpredictableincrease in the brightness (perhaps up to 10orders of magnitude) of a binary star system. Ina typical spiral galaxy like the Milky Way, as-trophysicists expect about 25 such eruptions tooccur each year. As Zwicky noted, the supernovawas a much more violent and rare stellar event.A star undergoing a supernova explosion tem-porarily shines with a brightness that is morethan 100 times more luminous than an ordinarynova. The supernova occurs in a galaxy like theMilky Way only about two or three times percentury. From 1937 to 1941 Zwicky engaged inan extensive search for such events beyond theMilky Way and personally discovered 18 extra-galactic supernovas. Until then, only about 12such events had been recorded in the entire his-tory of astronomy.

Since this early work by Zwicky and Baade,other astrophysicists have discovered more than800 extragalactic supernovas. Despite their

brilliance, not all supernovas are visible to naked-eye observers on Earth. The most famous naked-eye supernovas include the very bright new starreported by Chinese and Korean astronomers in1054; Tyco’s star, appearing in 1572; Kepler’sstar, appearing in 1604; and supernova 1987A,the most recent event, which took place in theLarge Magellan Cloud on February 23, 1987.Zwicky recognized that supernovas were incred-ibly interesting, yet violent celestial events.During a supernova explosion, the dying starmight become more than 1 billion times brighterthan the Sun.

In 1932 the British physicist Sir JamesChadwick (1891–1974) experimentally discov-ered the neutron. Zwicky recognized the astro-nomical significance of Chadwick’s discoveryand boldly presented an extremely visionary“neutron star” hypothesis in 1934. Specifically,Zwicky proposed that a neutron star might beformed as a by-product of a supernova explosion.He reasoned that the violent explosion and sub-sequent gravitational collapse of the dying star’score should create a compact object of such in-credible density that all the electrons and pro-tons become so closely packed together that theybecome neutrons. However, his daring hypoth-esis was essentially ignored for about threedecades. Then, in 1968, astronomers confirmedthe presence of the first suspected neutron star,a young optical pulsar, in the cosmic debris ofthe great supernova event of 1054. The discov-ery proved that the eccentric Zwicky was yearsahead of his contemporaries in suggesting a link-age between supernovas and neutron stars.

Zwicky also published the creative bookMorphological Cosmology in 1957. He receivedthe Gold Medal from the Royal AstronomicalSociety in 1973 for his contributions to moderncosmology. After spending almost five decadesin the United States, Zwicky died on February8, 1974, in Pasadena, California.

286

ASTRONAUTICS

Braun, Wernher Magnus vonEhricke, Krafft ArnoldGoddard, Robert HutchingsHohmann, WalterKorolev, Sergei PavlovichLagrange, Comte Joseph-LouisLaplace, Pierre-Simon, Marquis

de Leverrier, Urbain-Jean-JosephOberth, Hermann JuliusTereshkova, ValentinaTsiolkovsky, Konstantin

Eduardovich

ASTRONOMY

Adams, John CouchAdams, Walter SydneyAlfonso XÅngström, Anders JonasArago, Dominique-François-

JeanArgelander, Friedrich

Wilhelm AugustAristarchus of SamosAryabhataBaade, Wilhelm Heinrich

WalterBarnard, Edward EmersonBattani, al-Bayer, Johannes

Beg, Muhammed TaragaiUlugh

Bell Burnell, Susan JocelynBessel, Friedrich WilhelmBode, Johann ElertBok, Bartholomeus JanBradley, JamesBrahe, TychoBurbidge, Eleanor Margaret

PeacheyCampbell, William WallaceCannon, Annie JumpCassini, Giovanni DomenicoCharlier, Carl Vilhelm

LudvigClark, Alvan GrahamCopernicus, NicolasCurtis, Heber DoustDouglass, Andrew EllicottDrake, Frank DonaldDraper, HenryDyson, Sir Frank WatsonFleming, Williamina Paton

StevensGalilei, GalileoGalle, Johann GottfriedGill, Sir DavidHall, AsaphHalley, Sir EdmundHawking, Sir Stephen WilliamHerschel, Caroline Lucretia

Herschel, Sir John FrederickWilliam

Herschel, Sir WilliamHertzsprung, EjnarHewish, AntonyHubble, Edwin PowellHuggins, Sir WilliamJeans, Sir James HopwoodJones, Sir Harold SpencerKant, ImmanuelKapteyn, Jacobus CorneliusKepler, Johannesal-Khwarizmi, AbuKuiper, Gerard PeterLaplace, Pierre-Simon, Marquis

deLeverrier, Urbain-Jean-JosephLockyer, Sir Joseph NormanLowell, PercivalMessier, CharlesNewcomb, SimonOlbers, Heinrich Wilhelm

MatthäusOort, Jan HendrikPenzias, Arno AllenPiazzi, GiuseppePickering, Edward CharlesPtolemyReber, GroteRossi, Bruno BenedettoRussell, Henry Norris

ENTRIES BY FIELD

Entries by Field 287

Ryle, Sir MartinSagan, Carl EdwardScheiner, ChristophSchiaparelli, Giovanni

VirginioSchmidt, MaartenSchwabe, Samuel HeinrichSchwarzschild, KarlSecchi, Pietro AngeloShapley, HarlowSitter, Willem deSlipher, Vesto MelvinSomerville, Mary FairfaxTombaugh, Clyde WilliamWilson, Robert WoodrowWolf, Maximilian

ASTROPHYSICS

Alpher, Ralph AsherAmbartsumian, Viktor

AmazaspovichBell Burnell, Susan JocelynBethe, Hans AlbrechtBurbidge, Eleanor Margaret

PeacheyChandrasekhar,

SubrahmanyanEddington, Sir Arthur StanleyGiacconi, RiccardoHale, George ElleryLemaître, Abbé Georges-

ÊdouardRees, Sir Martin JohnRussell, Henry NorrisSagan, Carl EdwardSchmidt, MaartenSchwarzschild, KarlZwicky, Fritz

CHEMISTRY

Arrhenius, Svante AugustBunsen, Robert WilhelmCavendish, HenryUrey, Harold Clayton

COSMOLOGY

Alfvèn, Hannes Olof GöstaAlpher, Ralph AsherGamow, GeorgeHawking, Sir Stephen WilliamHubble, Edwin PowellLemaître, Abbé Georges-

Êdouard

ENGINEERING

Braun, Wernher Magnus vonEhricke, Krafft ArnoldHohmann, WalterKorolev, Sergei Pavlovich

ENVIRONMENTAL SCIENCE

Douglass, Andrew Ellicott

EXOBIOLOGY

Arrhenius, Svante AugustUrey, Harold Clayton

HISTORY

Alfonso X

LITERATURE

Aratus of Soli

MATHEMATICS

Adams, John CouchArago, Dominique-François-

JeanAristarchus of SamosAryabhataBattani, al-Beg, Muhammed Taragai

UlughBrahe, TychoCassini, Giovanni DomenicoCharlier, Carl Vilhelm LudvigDirac, Paul-Adrien-MauriceDoppler, Christian AndreasEuler, LeonhardGalilei, Galileo

Halley, Sir EdmundHawking, Sir Stephen

WilliamHerschel, Sir John Frederick

WilliamJeans, Sir James HopwoodKepler, Johannesal- Khwarizmi, AbuLagrange, Comte Joseph-LouisLaplace, Pierre-Simon,

Marquis deLeverrier, Urbain-Jean-JosephNewcomb, SimonNewton, Sir IsaacOberth, Hermann JuliusPtolemyScheiner, ChristophSitter, Willem deSomerville, Mary Fairfax

OPTICAL SCIENCE ANDINSTRUMENTATION

Clark, Alvan GrahamDraper, HenryFraunhofer, Joseph vonHale, George ElleryLippershey, HansNewton, Sir IsaacScheiner, Christoph

PHILOSOPHY

AristotleBruno, GiordanoHerschel, Sir John Frederick

WilliamKant, ImmanuelPlatoPtolemy

PHYSICS

Alfvén, Hannes Olof GöstaAlpher, Ralph AsherAlvarez, Luis WalterAnderson, Carl David

288 A to Z of Scientists in Space and Astronomy

Ångström, Anders JonasArago, Dominique-François-

JeanBoltzmann, LudwigCavendish, HenryClausius, Rudolf JuliusCompton, Arthur HollyDirac, Paul Adrien MauriceEinstein, AlbertEuler, LeonhardFowler, William AlfredFraunhofer, Joseph vonGalilei, GalileoGamow, GeorgeGoddard, Robert HutchingsHalley, Sir EdmundHawking, Sir Stephen William

Hertz, Heinrich RudolfHess, Victor FrancisHubble, Edwin PowellJeans, Sir James HopwoodKirchhoff, Gustav RobertLockyer, Sir Joseph

NormanMichelson, Albert AbrahamNewton, Sir IsaacOberth, Hermann JuliusPenzias, Arno AllenPickering, Edward CharlesPlanck, Max KarlRossi, Bruno BenedettoRyle, Sir MartinSagan, Carl EdwardStefan, Josef

Tsiolkovsky, KonstantinEduardovich

Van Allen, James AlfredWilson, Robert Woodrow

SPACE SCIENCES

Alfvén, Hannes Olof GöstaVan Allen, James AlfredRossi, Bruno Benedetto

SPECTROSCOPY

Bunsen, Robert WilhelmFraunhofer, Joseph vonHuggins, Sir WilliamKirchhoff, Gustav RobertLockyer, Sir Joseph NormanSecchi, Pietro Angelo

289

ARMENIA

Ambartsumian, ViktorAmazaspovich

AUSTRIA

Boltzmann, LudwigDoppler, Christian

AndreasHess, Victor FrancisStefan, Josef

BELGIUM

Lemaître, Abbé Georges-Êdouard

BULGARIA

Zwicky, Fritz

CANADA

Newcomb, Simon

DENMARK

Brahe, TychoHertzsprung, Ejnar

EGYPT

Ptolemy

FRANCE

Arago, Dominique-François-Jean

Laplace, Pierre-Simon,Marquis de

Leverrier, Urbain-Jean-JosephMessier, Charles

GERMANY (INCLUDES PRUSSIA)Baade, Wilhelm Heinrich

WalterBayer, JohannesBessel, Friedrich WilhelmBethe, Hans AlbrechtBode, Johann ElertBraun, Wernher Magnus vonBunsen, Robert WilhelmEhricke, Krafft ArnoldEinstein, AlbertFraunhofer, Joseph vonGalle, Johann GottfriedHerschel, Caroline LucretiaHerschel, Sir WilliamHertz, Heinrich RudolfHohmann, WalterKant, ImmanuelKepler, JohannesKirchhoff, Gustav RobertLippershey, HansMichelson, Albert AbrahamOlbers, Heinrich Wilhelm

MatthäusPenzias, Arno AllenPlanck Max Karl

Scheiner, ChristophSchwabe, Samuel HeinrichSchwarzschild, KarlWolf, Maximilian

GREAT BRITAIN

Adams, John CouchBell Burnell, Susan JocelynBradley, JamesBurbidge, Eleanor Margaret

PeacheyCavendish, HenryDirac, Paul Adrien MauriceDyson, Sir Frank WatsonEddington, Sir Arthur StanleyFleming, Williamina Paton

StevensGill, Sir DavidHalley, Sir EdmundHawking, Sir Stephen WilliamHerschel, Sir John Frederick

WilliamHewish, AntonyHuggins, Sir WilliamJeans, Sir James HopwoodJones, Sir Harold SpencerLockyer, Sir Joseph NormanNewton, Sir IsaacRees, Sir Martin JohnRyle, Sir MartinSomerville, Mary Fairfax

ENTRIES BY COUNTRY OF BIRTH

290 A to Z of Scientists in Space and Astronomy

GREECE

Aratus of SoliAristarchus of SamosAristotlePlato

INDIA

AryabhataChandrasekhar, Subrahmanyan

ITALY

Bruno, GiordanoCassini, Giovanni DomenicoGalilei, GalileoGiacconi, RiccardoLagrange, Comte Joseph-LouisPiazzi, GiuseppeRossi, Bruno BenedettoSchiaparelli, Giovanni

VirginioSecchi, Pietro Angelo

LITHUANIA

Argelander, Friedrich Wilhelm

NETHERLANDS

Bok, Bartholomeus JanKapteyn, Jacobus

CorneliusKuiper, Gerard PeterOort, Jan HendrikSchmidt, MaartenSitter, Willem de

PERSIA

Beg, Muhammed Taragai Ulughal-Khwarizmi, Abu

POLAND

Clausius, Rudolf JuliusEmmanuel

Copernicus, Nicolas

ROMANIA

Oberth, Hermann Julius

RUSSIA

Tereshkova, ValentinaTsiolkovsky, Konstantin

Eduardovich

SPAIN

Alfonso X

SWEDEN

Alfvèn, Hannes Olof GöstaÅngström, Anders JonasArrhenius, Svante AugustCharlier, Carl Vilhelm Ludvig

SWITZERLAND

Euler, Leonhard

SYRIA

Adams, Walter Sydney

TURKEY

Battani, al-

UKRAINE

Gamow, GeorgeKorolev, Sergei Pavlovich

UNITED STATES

Alpher, Ralph AsherAlvarez, Luis WalterAnderson, Carl DavidBarnard, Edward EmersonCampbell, William

WallaceCannon, Annie JumpClark, Alvan GrahamCompton, Arthur HollyCurtis, Heber DoustDouglass, Andrew EllicottDrake, Frank DonaldDraper, HenryFowler, William AlfredGoddard, Robert HutchingsHale, George ElleryHall, AsaphHubble, Edwin PowellLowell, PercivalPickering, Edward CharlesReber, GroteRussell, Henry NorrisSagan, Carl EdwardShapley, HarlowSlipher, Vesto MelvinTombaugh, Clyde WilliamUrey, Harold ClaytonVan Allen, James AlfredWilson, Robert Woodrow

291

AUSTRALIA

Reber, Grote

AUSTRIA

Boltzmann, LudwigDoppler, Christian AndreasHess, Victor FrancisStefan, Josef

BELGIUM

Lemaître, Abbé Georges-Êdouard

DENMARK

Brahe, TychoHertzsprung, Ejnar

EGYPT

Ptolemy

FRANCE

Arago, Dominique-François-Jean

Cassini, Giovanni DomenicoLagrange, Comte Joseph-

LouisLaplace, Pierre-Simon,

Marquis deLeverrier, Urbain-Jean-

JosephMessier, Charles

GERMANY

Argelander, Friedrich Wilhelm August

Bayer, JohannesBessel, Friedrich WilhelmBode, Johann ElertBunsen, Robert WilhelmClausius, Rudolf Julius

EmmanuelFraunhofer, Joseph vonGalle, Johann GottfriedHertz, Heinrich RudolfHohmann, WalterKant, ImmanuelKepler, JohannesKirchhoff, Gustav RobertOberth, Hermann JuliusOlbers, Heinrich Wilhelm

MatthäusPlanck, Max KarlScheiner, ChristophSchwabe, Samuel HeinrichSchwarzschild, KarlWolf, Maximilian

GREAT BRITAIN

Adams, John CouchBell Burnell, Susan JocelynBradley, JamesCavendish, HenryChandrasekhar, Subrahmanyan

Dirac, Paul Adrien MauriceDyson, Sir Frank WatsonEddington, Sir Arthur

StanleyHalley, Sir EdmundHerschel, Caroline LucretiaHerschel, Sir WilliamHerschel, Sir John Frederick

WilliamHewish, AntonyHuggins, Sir WilliamJeans, Sir James HopwoodJones, Sir Harold SpencerLockyer, Sir Joseph NormanNewton, Sir IsaacRees, Sir Martin JohnRyle, Sir MartinSomerville, Mary Fairfax

GREECE

Aratus of SoliAristarchus of SamosAristotlePlato

INDIA

Aryabhata

ITALY

Bruno, GiordanoGalilei, Galileo

ENTRIES BY COUNTRY OF MAJORSCIENTIFIC ACTIVITY

292 A to Z of Scientists in Space and Astronomy

Piazzi, GiuseppeSchiaparelli, Giovanni

VirginioSecchi, Pietro Angelo

NETHERLANDS

Kapteyn, Jacobus CorneliusLippershey, HansOort, Jan HendrikSitter, Willem de

PERSIA

Beg, Muhammed TaragaiUlugh

al-Khwarizmi, Abu

POLAND

Copernicus, Nicolas

RUSSIA

Ambartsumian, ViktorAmazaspovich

Euler, LeonhardKorolev, Sergei PavlovichTereshkova, ValentinaTsiolkovsky, Konstantin

Eduardovich

SPAIN

Alfonso X

SOUTH AFRICA

Gill, Sir DavidHerschel, Sir John Frederick

WilliamSitter, Williem de

SWEDEN

Alfvén, Hannes Olof GöstaÅngström, Anders JonasArrhenius, Svante AugustCharlier, Carl Vilhelm

LudvigDirac, Paul Adrien Maurice

SWITZERLAND

Einstein, Albert

SYRIA

Battani, al-

UNITED STATES

Adams, Walter SydneyAlpher, Ralph AsherAlvarez, Luis WalterAnderson, Carl DavidBaade, Wilhelm Heinrich

WalterBarnard, Edward EmersonBethe, Hans AlbrechtBok, Bartholomeus JanBraun, Wernher

Magnus vonBurbidge, Eleanor Margaret

PeacheyCampbell, William WallaceCannon, Annie JumpChandrasekhar,

SubrahmanyanClark, Alvan GrahamCompton, Arthur HollyCurtis, Heber DoustDouglass, Andrew Ellicott

Drake, Frank DonaldDraper, HenryEhricke, Krafft ArnoldEinstein, AlbertFleming, Williamina Paton

StevensFowler, William AlfredGamow, GeorgeGiacconi, RiccardoGoddard, Robert

HutchingsHale, George ElleryHall, AsaphHubble, Edwin PowellKuiper, Gerard PeterLowell, PercivalMichelson, Albert

AbrahamNewcomb, SimonPenzias, Arno AllenPickering, Edward CharlesReber, GroteRossi, Bruno

BenedettoRussell, Henry NorrisSagan, Carl EdwardSchmidt, MaartenShapley, HarlowSlipher, Vesto MelvinTombaugh, Clyde

WilliamUrey, Harold ClaytonVan Allen, James AlfredWilson, Robert

WoodrowZwicky, Fritz

293

499–400 B.C.E.Plato

399–300 B.C.E.Aratus of SoliAristarchus of SamosAristotle

100–0 B.C.E.Ptolemy

400–499Aryabhata

700–799al-Khwarizmi, Abu

800–900Battani, al-

1200–1299Alfonso X

1300–1399Beg, Muhammed Taragai

Ulugh

1400–1499Copernicus, Nicolas

1500–1599Bayer, JohannesBrahe, TychoBruno, GiordanoGalilei, GalileoKepler, JohannesLippershey, HansScheiner, Christoph

1600–1699Bradley, JamesCassini, Giovanni DomenicoHalley, Sir EdmundNewton, Sir Isaac

1700–1799Arago, Dominique-François-

JeanArgelander, Friedrich Wilhelm

AugustBessel, Friedrich WilhelmBode, Johann ElertCavendish, HenryEuler, LeonhardFraunhofer, Joseph vonHerschel, Caroline LucretiaHerschel, Sir WilliamHerschel, Sir John Frederick

WilliamKant, ImmanuelLagrange, Comte Joseph-Louis

Laplace, Pierre-Simon,Marquis de

Messier, CharlesOlbers, Heinrich Wilhelm

MatthäusPiazzi, GiuseppeSchwabe, Samuel HeinrichSomerville, Mary Fairfax

1800–1809Doppler, Christian Andreas

1810–1819Adams, John CouchÅngström, Anders JonasBunsen, Robert WilhelmGalle, Johann GottfriedLeverrier, Urbain-Jean-JosephSecchi, Pietro Angelo

1820–1829Clausius, Rudolf Julius

EmmanuelHall, AsaphHuggins, Sir WilliamKirchhoff, Gustav Robert

1830–1839Clark, Alvan GrahamDraper, HenryLockyer, Sir Joseph Norman

ENTRIES BY YEAR OF BIRTH

294 A to Z of Scientists in Space and Astronomy

Newcomb, SimonSchiaparelli, Giovanni

VirginioStefan, Josef

1840–1849Boltzmann, LudwigGill, Sir DavidPickering, Edward Charles

1850–1859Arrhenius, Svante AugustBarnard, Edward EmersonFleming, Williamina Paton

StevensHertz, Heinrich RudolfKapteyn, Jacobus CorneliusLowell, PercivalMichelson, Albert AbrahamPlanck, Max KarlTsiolkovsky, Konstantin

Eduardovich

1860–1869Campbell, William WallaceCannon, Annie JumpCharlier, Carl Vilhelm LudvigDouglass, Andrew EllicottDyson, Sir Frank WatsonHale, George ElleryWolf, Maximilian

1870–1879Adams, Walter SydneyCurtis, Heber DoustEinstein, Albert

Hertzsprung, EjnarJeans, Sir James HopwoodRussell, Henry NorrisSchwarzschild, KarlSitter, Willem deSlipher, Vesto Melvin

1880–1889Eddington, Sir Arthur

StanleyGoddard, Robert HutchingsHess, Victor FrancisHohmann, WalterHubble, Edwin PowellShapley, Harlow

1890–1899Baade, Wilhelm Heinrich

WalterCompton, Arthur HollyJones, Sir Harold SpencerLemaître, Abbé Georges-

ÊdouardOberth, Hermann JuliusUrey, Harold ClaytonZwicky, Fritz

1900–1909Alfvén, Hannes Olof GöstaAmbartsumian, Viktor

AmazaspovichAnderson, Carl DavidBethe, Hans AlbrechtBok, Bartholomeus JanDirac, Paul Adrien MauriceGamow, George

Korolev, Sergei PavlovichKuiper, Gerard PeterOort, Jan HendrikRossi, Bruno BenedettoTombaugh, Clyde William

1910–1919Alvarez, Luis WalterBraun, Wernher Magnus vonBurbidge, Eleanor Margaret

PeacheyChandrasekhar,

SubrahmanyanEhricke, Krafft ArnoldFowler, William AlfredReber, GroteRyle, Sir MartinVan Allen, James Alfred

1920–1929Alpher, Ralph AsherHewish, AntonySchmidt, Maarten

1930–1939Drake, Frank DonaldGiacconi, RiccardoPenzias, Arno AllenSagan, Carl EdwardTereshkova, ValentinaWilson, Robert Woodrow

1940–1949Bell Burnell, Susan JocelynHawking, Sir Stephen WilliamRees, Sir Martin John

295

CHRONOLOGY

296 A to Z of Scientists in Space and Astronomy

Konstantin Eduardovich Tsiolkovsky

Gustav Robert Kirchhoff

Johann Elert Bode

Marquis Pierre-Simon de Laplace

Caroline Lucretia Herschel

Heinrich Wilhelm Matthäus Olbers

Mary Fairfax Somerville

Dominique-François-Jean AragoJoseph von Fraunhofer

Friedrich Wilhelm Bessel

Samuel Heinrich Schwabe

Sir John Frederick William Herschel

Friedrich Wilhelm August Argelander

Christian Andreas Doppler

Urbain-Jean-Joseph Leverrier

Robert Wilhelm Bunsen

Anders Jonas Ångström

Johann Gottfried Galle

Pietro Angelo Secchi

John Couch Adams

Rudolf Julius Emmanuel Clausius

Gustav Robert Kirchhoff

Sir William Huggins

Asaph Hall

Simon Newcomb

Alvan Graham Clark

Giovanni Virginio Schiaparelli

Josef Stefan

Sir Joseph Norman Lockyer

Henry Draper

Sir David Gill

Ludwig Boltzmann

Edward Charles Pickering

Jacobus Cornelius Kapteyn

Albert Abraham Michelson

Percival Lowell

Heinrich Rudolf Hertz

Williamina Paton Stevens Fleming

Edward Emerson Barnard

Konstantin Eduardovich Tsiolkovsky

Max Karl Planck

Svante August Arrhenius

Carl Vilhelm Ludvig Charlier

William Wallace Campbell

Maximilian Wolf

1750 1800 1850 1900 1950 2000

Chronology 297

298 A to Z of Scientists in Space and Astronomy

299

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Weedman, Daniel W. Quasar Astronomy. Cambridge,U.K.: Cambridge University Press, 1986.

Weinberg, Steven. The First Three Minutes: A Mod-ern View of the Origin of the Universe. 2d ed. Cam-bridge, Mass.: Perseus Publishing, 1993.

Westfall, Richard. The Life of Isaac Newton. Cam-bridge, U.K.: Cambridge University Press,1993.

Wheeler, J. Craig. Cosmic Catastrophes: Supernovae,Gamma-Ray Bursts, and Adventure in Hyperspace.Cambridge, U.K.: Cambridge University Press,2000.

Wilson, Fred L. Science and Human Values: Aristotle.Rochester Institute of Technology. Available on-line. URL: http://www.rit.edu/~flwstv/aristotle1.html. Accessed March 10, 2004.

Wolfram Research. Available on-line. URL: http://scienceworld.wolfram.com. Accessed March 10,2004.

Yerkes Observatory University of Chicago. Availableon-line. URL: http://astro.uchicago.edu/yerkes.Accessed March 10, 2004.

Yount, Lisa, Twentieth-Century Women Scientists. NewYork: Facts On File, 1996.

Zeilik, Michael. Astronomy: The Evolving Universe.8th ed. New York: John Wiley & Sons, 1999.

305

INDEX

A

Aachen Technical University169

Abbe Medal/Memorial Prize165

aberration of starlight 58–59,74, 104, 106, 233

Academia des Ciencias deLisboa 96

Académie des Sciences 20,67, 77, 97, 146, 196–199,212, 259, 266. See alsoJanssen Medal; LalandeMedal; Paris Academy;Poncelet Prize

Academy of Mines andForests 98

Accademia delle Scienze diTorino 96

Accademia Nazionale deiLincei (Rome) 97, 125

Achilles 281–282Adams, John Couch 1–5, 2,

155Adams, Walter Sydney 5,

5–7Adams Prize, Cambridge

University 175–176

Airy, George Biddell 2–4,156

Albategnius 38–40Albert Einstein World Award

of Science Medal 71Albert Medal 68Albertus University 45Aldrin, Edwin (Buzz) 64Alexander the Great (king of

Macedonia) 25, 27Alexander VII (pope) 76Alfonso X (king of León and

Castile) 7–8Alfvén, Hannes Olof Gösta

8–10, 9Alfvén waves 8–9Allegheny Observatory,

Curtis and 94The Almagest (Ptolemy)

38–39, 186, 239–241Alpha Centauri 41Alpher, Ralph Asher 10–12,

128Alvarez, Luis Walter 12–15,

13Alvarez, Walter 12–14Alvarez hypothesis 12–15Amalthea 36Ambartsumian, Viktor

Amazaspovich 15–16

American Academy of Artsand Sciences 103, 168,232, 246. See also RumfordGold Medal

American Academy ofSciences 194

American Association for the Advancement ofScience (AAAS) 35, 89,94, 103, 201. See alsoKepler Medal

American Association ofUniversity Women 70–71,76, 201

American Association ofVariable Star Observers201, 234

American AstronauticalSociety 252

American Astronomical andAstrophysical Society 201

American AstronomicalSociety 44, 70, 83, 94, 217,243–244, 252, 282

American Chemical SocietyWillard Gibbs Medal 29

American Institute of Physics244

American Institute of theCity of New York 18

Note: Page numbers in boldface indicate main topics. Page numbers in italic refer to illustrations.

American MathematicalSociety 217

American Physical Society89, 96, 119, 232

American Society of SwedishEngineers 18

Amyntas III (king ofMacedonia) 25

Analytical Society 153Anaximander 237–238Anderson, Carl David

16–18androcell, Ehricke and

109–110Andromeda Galaxy 32–33,

266androsphere 109Ångström, Anders Jonas

18–20, 19Anne (queen of Great

Britain) 145, 220Annie J. Cannon Award in

Astronomy 70–71, 76anthropic principle 244Antigonus Gonatus (king of

Macedonia) 22antimatter 17–18, 96aperture synthesis 250aphelion point 39Apollo Project 61Applied Physics Laboratory

276–277Arago, Dominique-François-

Jean 2, 20–22, 204Aratus of Soli 22Archimedes 24, 90Arecibo Observatory 102Argelander, Friedrich

Wilhelm August 22–24Aristarchus of Samos 24,

90–91, 240Aristocles. See PlatoAristotle 24–27, 123–126,

239–240

Arizona, University of99–100, 194

Arizona State College 270Armenian Academy of

Sciences 16Armstrong, Neil 64Arrhenius, Johan 27Arrhenius, Svante August

27, 27–29Aryabhata 29–30asteroids

Alvarez and 12–15Baade and 31, 34Bessel and 47Bode and 53Galle and 127Gill and 133Jones and 177Newcomb and 215Olbers and 224Piazzi and 53, 232–233Sagan and 252Schiaparelli and 254Wolf and 281–282

astrolabe 187Astronomical Society of

France 118, 224Astronomical Society of

London 154, 159Astronomical Society of

Mexico 118Astronomical Society of the

Pacific 94, 102. See alsoBruce Gold Medal

astronomical unit (AU) 51,127, 132, 177

Astronomische Gesellschaft23, 82–83, 103

astrophotography 34, 133,180–182, 258, 269, 281

astrophysics, term 142astropolis 109–110Atkinson, Robert d’Escourt

48

Australian NationalUniversity 55

B

Baade, Wilhelm HeinrichWalter 31–34, 283–285

Babbage, Charles 153–154background radiation 11–12,

127, 129, 149, 229–232,280–281. See also blackbodyradiation

Baikonur Cosmodrome 190Barnard, Edward Emerson

34–38, 84Barnard Astronomical

Society 37Barnard Medal for

Meritorious Service toScience 113, 119

Barnard’s Star 37Basel, University of 115Battani, al- 38–40Bayer, Johannes 40–41Beatrice M. Tinsley Prize 44Becquerel, A. Henri 28Beg, Muhammed Taragai

Ulugh 41–42Belgian Royal Academy 168Bell, Alexander Graham

213Bellarmine, Robert 125Bell Burnell, Susan Jocelyn

42–44, 166–168Bell Laboratories 230–232Bergman, Lorraine 18Berlin, University of 62, 85,

112, 126, 160, 188–189,213, 235–236

Berlin Academy of Sciences45, 47, 50, 115, 196

Berliner AstronomischesJahrbuch 50, 52–53

306 A to Z of Scientists in Space and Astronomy

Berlin Institute ofTechnology 62

Berlin Observatory 51, 53,126, 203–204

Berlin Technical University108

Bernoulli, Johann 115Bessel, Friedrich Wilhelm

23, 44–47Bethe, Hans Albrecht 11,

47–50big bang theory 10–12, 49,

127–129, 147, 171,201–203, 231–232, 255

binary stars 154, 159, 193blackbody radiation 11–12,

189, 236, 267. See alsobackground radiation

black holes 147, 149,243–244, 257

blinking comparator 269Bode, Johann Elert 50–53Bode-Flamsteed atlas 53Bohr, Neils 81, 96, 128, 236Bok, Bartholomeus Jan

53–55, 54, 193Bologna, University of 76, 245Bolton, John 34Boltzmann, Ludwig 28,

55–58, 56, 267Bond, George Phillips 142Bond, William 142Bonn, University of 23, 86,

161Bonnet, Charles 51Bonn survey 23Born, Max 96Bouguer, Pierre 21Bowen, Ira Sprague 173, 207Bower Science Medal 244Bradley, James 46, 58–59Brahe, Otto 60Brahe, Tycho 40, 59–61,

183

Braid, James W. 35Brashear, J. A. 140–141Braun, Wernher Magnus von

61, 61–64, 108, 191, 222,223, 278

Brera Observatory 254Breslau, University of 188Breslau Observatory 127Bristol, University of 95British Association for the

Advancement of Science3, 155, 176

British Chemical SocietyFaraday Medal 29

Broughman, Henry 80Bruce, Catherine Wolfe 37,

282Bruce, Eliza 5Bruce Gold Medal,

Astronomical Society ofthe Pacific 282

Adams and 7Ambartsumian and 16Baade and 34Barnard and 37Bethe and 50Bok and 55Burbidge and 71Campbell and 74Charlier and 83Dyson and 105Eddington and 107Fowler and 119Giacconi and 131Gill and 133–134Hertzsprung and 163Jones and 178Kapteyn and 182Newcomb and 217Oort and 228Pickering and 234Reber and 243Rees and 244Russell and 249

Ryle and 250Schiaparelli and 254Schmidt and 255Shapley and 261Sitter and 263Slipher and 266Wolf and 282

Brucia 282Bruno, Giordano 64–66, 92Bunsen, Robert Wilhelm 66,

66–68, 187–189Bunsen burner 66–67Burbidge, Eleanor Margaret

Peachey 68–71, 69, 119Burbidge, Geoffrey 68–70Burke, Grace 171Burnell, Martin 43, 168Burnham, S. W. 35–37Byurakan Astrophysical

Observatory 15–16

C

Caen, University of 197calculus, Newton and

218–220California, University of

9–10, 13–14, 70, 72–74,102, 273, 275

California Institute ofTechnology (Caltech)17–18, 69, 118–119, 142,255–256, 280, 283–284

California State University109

Calvert, Rhoda 35Cambridge Observatory 2,

5Cambridge University

Adams and 1–2, 5Bell Burnell and 43Bethe and 47Cavendish and 78

Index 307

Cambridge University(continued)

Chandrasekhar and 80–81Dirac and 95–97Dyson and 104Eddington and 106Hawking and 147Herschel and 153Hewish and 166–168Jeans and 175Jones and 177Lemaítre and 202Newton and 218–219Rees and 244Russell and 248Ryle and 249

Campani, Giuseppe 77Campbell, Betsey (Bess) 72,

74Campbell, William Wallace

72–74, 73Cannon, Annie Jump

74–76, 75Cape of Good Hope

Observatory 132–133,154–155, 177, 180–181, 262

Carnegie Institution100–101, 142, 276

Carnot, Sadi 86Caroline (queen of Great

Britain) 146Carte du Ciel project 104, 133Case School in Applied

Science 213Cassini, Giovanni Domenico

76–78, 144catalogs

Argelander and 22–24Bayer and 40–41Beg and 42Bessel and 46–47Bode and 50, 52–53Campbell and 74Cannon and 74–76

Fleming and 117Gill and 133Halley and 144Herschel and 151–152,

156, 158–159Kapteyn and 180–181Messier and 211–212Newcomb and 216Piazzi and 233Ryle and 249–250Secchi and 258Zwicky and 285

Catherine II (empress ofRussia) 116

Cavendish, Henry 78–80Cavendish Laboratory 68,

80, 88, 128, 167, 249Celsius, Anders 19Centaurus A 34Centaur vehicle 107, 109Cepheid variables 32–33,

201, 260Ceres 53, 232–233cesium 68, 188Chadwick, James 285Challis, James 2–4Chandrasekhar,

Subrahmanyan (Chandra)80–82, 85, 107, 220

Chandrasekhar’s limit80–82, 149

Charles II (king of England)144

Charlier, Carl VilhelmLudvig 82–83

Chéseaux, Jean-Philippe Loysde 224

Chiaramonti, Luigi 232Chicago, University of 13,

81, 88, 141, 170–171,193–194, 214, 251, 273. Seealso Yerkes Observatory

Christina (queen of Sweden)77

circular cosmology. Seespherical cosmology

City College of New York229

Clark, Alvan Graham83–85

Clark University 136–138,214

classification systems. Seecatalogs

Clausius, Rudolf JuliusEmmanuel 57, 85, 85–87,235

Clavius, Christopher 39Clement IX (pope) 77Cocconi, Giuseppi 101Colgate University 18College of the Pacific 92Collier Trophy in Aviation 15Colorado, University of 72,

129Columbia University 229,

273Columbus, Christopher 237Coma Cluster 284comets

Barnard and 35–36Bessel and 46Bode and 52Galle and 126Halley and 144–146Herschel (Caroline) and

150, 152, 159Kepler and 182Messier and 211–212Olbers and 224Oort and 227–228

Compton, Arthur Holly 87,87–89

Conklin, Evelina 141contact binaries 193Conti, Vittoria 196–197Copenhagen, University of

60–61

308 A to Z of Scientists in Space and Astronomy

Copenhagen PolytechnicInstitute 162

Copernicus, Nicolas 8,89–92, 90, 122, 125,182–184, 253

Copley Medal, Royal SocietyArago and 21Bunsen and 68Cavendish and 80Clausius and 87Dirac and 96Einstein and 113Herschel and 154–155Hubble and 174Leverrier and 204Michelson and 214Newcomb and 217Planck and 236

Cordoba Survey 24Cornell University 48, 50,

101–102, 245, 251–252Cosimo II (grand duke of

Tuscany) 125Cosmic Background Explorer

(COBE) 12, 149, 281cosmic egg 201–202cosmic rays 17, 89, 164–165,

244, 246, 276–277cosmology. See also Big Bang

theory; heliocentriccosmology

Alfvén and 9–10Aratus and 22Aristotle and 26Aryabhata and 29–30Battani and 38–39Bruno and 65Charlier and 83Clausius and 85–87Copernicus and 89–92Galileo and 122,

124–125Hawking and 146–150Hubble and 170–172

Jeans and 175Kant and 179Kapteyn and 181Kepler and 182–186Lemaître and 201–203Plato and 238–239Ptolemy and 240–241

Crab Nebula, Messier and211–212

Cracow, University of 89–90Cresson Gold Medal, Franklin

Institute 18, 243, 247Crick, Francis 129Curie, Marie 28Curie, Pierre 28Curtis, Heber Doust 32–33,

92, 92–94, 93, 93, 94, 259,261

Curtis, Mary D. Rapier 94

D

Daguerre, Louis 21d’Alembert, Jean 198Dançay, Charles 60dark matter 243, 263,

283–285dark stars 47d’Arrest, Heinrich Ludwig 4,

126Dartmouth College 6Darwin, Charles 153–154Davy Medal, Royal Society

29, 68Dawes, William 3Dearborn Observatory 84, 140Deimos 84, 142–143Delaunay, Charles-Eugene

204Delisle, Joseph Nicolas 211Desaga, Peter 67Descartes, René 193Deybe, Peter 283

Dicke, Robert 231, 281Die Frau im Mond 62, 108,

223Dione 77Dirac, Gabriel Andrew 96Dirac, Paul Adrien Maurice

95–97Disney, Walt 63Doppler, Christian Andreas

97–99Doppler effect 74, 97–99,

171, 173, 254, 266Doraiswamy, Lalitha 81Dornberger, Walter 62Doroschkevich, A. G. 11Douglass, Andrew Ellicott

99–101, 209Drake, Frank Donald

101–102Draper, Ann Palmer 234Draper, Henry 102–103Draper, John William 102Dreyer, Johan 212Dreyer, L. E. 156Druyan, Ann 251Dudley Observatory 12Dugan, Raymond 248Dunlop, James 34Dutcher, Mary 119dwarf galaxies 261dwarf stars 6, 163, 248Dyson, Frank Watson

104–105, 106

E

eclipsing binaries 248, 260École Militaire 198École Polytechnique 20, 197,

203, 213Eddington, Arthur Stanley

82, 106–107, 107, 147,202, 262

Index 309

Eddington Medal, RoyalAstronomical Society 119,168, 203

Edinburgh Medal 44Edlund, Eric 28Edson, Patricia 270education, Einstein on

110–111Ehricke, Ingebord 109Ehricke, Krafft Arnold

107–110Einstein, Albert 110–114,

171, 202, 283Einstein, Elsa 113Elizabeth I (queen of

England) 65Elizabeth II (queen of Great

Britain) 178, 244, 250Ellerman, Ferdinand 37elliptical orbits 144–145,

184–185Enceladus 159Encke, Johann Franz 126, 253entropy 57, 85–87Erikson, Kerstin Maria 9Euclid 263Eudoxus of Cnidos 22,

25–26, 239Euler, Leonhard 114–116,

195–196Europa 275European Southern

Observatory 131event horizon 257Explorer I 64, 276–277, 278extraterrestrial life 27, 29,

101–102, 147, 149–150,208–210, 273–275

F

Fairfield, Priscilla 54Fälthammar, Carl-Gunne 9

Faraday, Michael 21,153–154

Faraday Medal, BritishChemical Society 29

Federal Institute ofTechnology 283

Feoktistov, Konstantin191–192

Ferdinand II (Holy RomanEmperor) 253

Ferdinand (king of Sicily)53

Ferguson, James 151, 157Fermi, Enrico 89, 245Fizeau, Armand 98Fizeau, Hippolyte 22Flamsteed, John 23, 41, 52,

59, 144–146, 152, 220Fleming, James 117Fleming, Williamina (Mina)

Paton Stevens 117–118Flora 127Florence, University of

245–246Florida State University 97Ford, Gerald 119Fordham University 165Fortin, Jean 52–53Foucault, Léon 22Fowler, Ralph H. 80, 95Fowler, William Alfred

118–120France, Collège de 213Franck, James 96Francqui Award 202Frankfurt, University of 47Franklin Institute. See Bower

Science Medal; CressonGold Medal; FranklinMedal; Kepler Medal

Franklin Medal, FranklinInstitute 89, 214

Fraunhofer, Joseph von120–121

Fraunhofer lines 67,120–121, 188

Frederick II (king ofDenmark) 60

Frederick II (king of Prussia)196–197

Frederick the Great (king ofPrussia) 115–116

Fresnel, Augustine 20–21Friedmann, Alexander 202Friedrich Wilhelm III (king

of Prussia) 45Friedrich Wilhelm IV (king

of Prussia) 23Frost, Edwin B. 6Fuller, Sarah Parker 193

G

Gagarin, Yuri 191Galilei, Galileo 4, 26, 92,

122–126, 123, 184–185,205, 241, 252

Galilei, Vincenzo 122Galle, Johann Gottfried 4,

126–127, 204Gamba, Marina 124gamma rays 44, 87–89Gamow, George 10–11,

127–129, 128Gassendi, Pierre 61Gauss, Carl Friedrich 187,

224, 233Gauss, Johann 45Gay-Lussac, Joseph 203Geiger, Hans Wilhelm 108Gemini project 191general relativity theory 7,

113, 258George III (king of Great

Britain) 151–152, 158George of Trebizond 240Georgetown University 259

310 A to Z of Scientists in Space and Astronomy

George VI (king of GreatBritain) 178

George WashingtonUniversity 10, 128

Giacconi, Riccardo129–132, 130, 244, 246

giant stars 6, 81, 248Gill, David 132–134,

180–181Gill, Isabel 132–133Glasgow, University of 42Goddard, Robert Hutchings

134–139, 135, 223Gold Medal, Académie des

Sciences 266Gold Medal, American

Institute of the City of NewYork 18

Gold Medal, Italian PhysicalSociety 247

Gold Medal, RoyalAstronomical Society(Britain)

Adams and 7Ambartsumian and 16Baade and 34Barnard and 37Bessel and 47Campbell and 74Dyson and 105Giacconi and 131Gill and 133Hall and 143Herschel and 152, 154Hertzsprung and 163Hubble and 174Huggins and 173Jeans and 176Jones and 178Kapteyn and 182Michelson and 214Newcomb and 217Oort and 228Pickering and 234

Rees and 244Russell and 249Ryle and 250Schiaparelli and 254Schmidt and 255Schwabe and 257Shapley and 261Sitter and 263Slipher and 266Wolf and 282Zwicky and 285

Gold Medal, Royal Society113

Goodricke, John 32–33Göttingen, University of 31,

34, 45, 66, 128, 223–224,257

Göttingen Observatory 163gravitation

Cavendish and 79Chandrasekhar and 81Einstein and 112–113Galileo and 123Laplace and 197–199Newton and 218–219Sitter and 262

Graz, University of 56,164–165

Gregory, David 51Gregory XIII (pope) 39Grieg, Samuel 264Groningen, University of 54,

180–181, 226, 254, 262Groningen Astronomical

Laboratory 262Gsell, Abigail 116Gsell, Katharina 115–116Guadalupa Almendaro Medal

118Guggenheim, Daniel 139G. Unger Verlesen Prize 119Gunter Löser Medal,

International AstronauticalFederation 110

Gustavus Adolphus College18

Gylden, Johan A. H. 82

H

Hale, George Ellery 6,36–37, 84, 140–142, 171

Hale Observatories 255Hale Solar Laboratory 6–7Hall, Asaph 84, 142–143,

216Halle, University of 85Halley, Edmund 144–146,

195, 219Halley’s Comet 44, 146, 155,

211–212Hamburg Observatory 31Hangen, Johanna 45Harriot, Thomas 44Harun al-Rashid (caliph of

Baghdad) 38Harvard Boyden Station 55Harvard Classification

System 233–234Harvard College Observatory

Bok and 54–55Cannon and 74Douglass and 99Fleming and 117Hale and 141Hall and 142–143Kuiper and 193Leavitt and 200–201Lowell and 209Pickering and 233–234Shapley and 259, 261

Harvard-Smithsonian Centerfor Astrophysics 131

Harvard SouthernHemisphere Observatory99–100, 234

Harvard Standard 201

Index 311

Harvard University 101,143, 208, 215, 233, 251

Hawaii, University of 36Hawking, Stephen William

95, 146–150Hebrew University 114Heidelberg, University of 67,

188, 213, 223, 281Heisenberg, Werner 95Helen B. Warner Prize for

Astronomy 70heliocentric cosmology 24,

89–92, 122, 124–125,182–186

helium 206–207Helmholtz, Herman von 160Helsinki Observatory 23Henri III (king of France) 65Henry, Joseph 215Henry Draper Catalog 76,

103, 117, 234Henry Draper Medal,

National Academy ofSciences

Adams and 7Campbell and 74Cannon and 76Hubble and 174Michelson and 214Penzias and 232Pickering and 234Russell and 249Ryle and 250Shapley and 261Slipher and 266Wilson and 281

Henry Draper Memorial Fund75, 103

Herman, Robert 11–12Hermes Project 63Herpyllis 25Herschel, Alexander 151,

156–157

Herschel, Caroline Lucretia150–153, 153–154,156–159

Herschel, John FrederickWilliam 3–4, 47, 152,153–156

Herschel, Mary Pitt153–154, 159

Herschel, William 1, 52,150–153, 156–160

Herschel Medal, RoyalAstronomical Society 44,232, 281

Hertz, Heinrich Rudolf 160,160–161

Hertzsprung, Ejnar161–164, 162, 193, 263

Hertzsprung-Russell (HR)diagram 161–164, 247–249

Hesperia 254Hess, Victor Francis 164,

164–165Hevelius, Johannes 52Hewish, Antony 43,

165–168, 166, 249Hidalgo 31Hipparchus 22, 239–240Hock, Suzanne 176Hohmann, Walter 168–170Holden, Edward 35–36Holland Academy of

Sciences 87Hooke, Robert 219Hösling, Marga von 235, 237Houtermans, Fritz 48Hoyle, Fred 11, 49, 68, 119Hubble, Edwin Powell 5,

92–94, 170, 170–172, 266Huggins, William 172–174,

207Hughes Medal, Royal Society

89, 168Hulst, Hendrik van de 227

Humboldt, Alexander von256

Hume, David 112Hummel, Mathilde 223Huxley, Aldous 220Huygens, Christiaan 219Huygens Medal, Holland

Academy of Sciences 87Hyades 163hydrogen 20, 78–80

I

Iapetus 77Icarus 34Icarus project 252Imperial Academy of

Sciences, Vienna 98Imperial College 244Imperial Russian Academy

259Index Liber Prohibitorum

65–66, 92Indiana, University of 265Indian Academy of Science

96Indiana University 129Indian National Science

Academy 168inertia 218Innsbruck, University of 165Institut de France 96Institute of Astronomy

(Cambridge University)244

Institute of TheoreticalPhysics 273

International AstronauticalFederation, Gunter LöserMedal 110

International AstronomicalUnion 16, 54, 177, 263

312 A to Z of Scientists in Space and Astronomy

International Council ofScientific Unions 16

Io 36Ionian philosophers 237–238Iowa, University of 276–279iridium anomaly 14Iris 133island universes, Kant and

179–180Italian Physical Society 247

J

Jackiw, R. W. 50Jackson-Gwilt Medal, Royal

Astronomical Society 243James II (king of Great

Britain) 219–220Jansky, Karl 242Jansky Prize 243, 255Janssen, Pierre-Jules-César

21, 206–208Janssen, Zacharias 206Janssen Medal, Académie des

Sciences 16, 174, 194Jeans, James Hopwood 5,

175–176, 236jet-assisted takeoff (JATO)

139, 190Jet Propulsion Laboratory

(JPL) 64, 102, 252Jewitt, David C. 36Johansson, Maria 28John Ericsson Medal,

American Society ofSwedish Engineers 18

John F. Kennedy AstronauticsAward 252

John Paul II (pope) 126Johns Hopkins University

216, 273, 276–277Johnson, Lyndon B. 15

Joliot-Curie Gold Medal 268Jones, Bryn 52Jones, Harold Spencer 133,

177–178Jörgensdatter, Kirsten 60Juenemann, Luise 169Juno I 64Jupiter 77, 82, 122, 124, 185,

262Justinian (emperor of Rome)

239

K

Kaiser Wilhelm Institute 237Kalinga Prize 129Kansas, University of 270Kant, Immanuel 179–180Kapitsa, Pyotr 232, 281Kapteyn, Jacobus Cornelius

133, 180–182, 226,262–263

Karlshoven, Catharina 181Karlsruhe Polytechnic 160Kassel, University of 67Keeler, James 35Kellogg Radiation Laboratory

118Kelvin, William Thompson

86Kennedy, John F. 18, 64,

191–192Kenwood Physical

Observatory 141Kepler, Johannes 40, 61, 92,

124–125, 182, 182–186,219

Kepler, Katharina 184Kepler Medal, American

Association for theAdvancement of Science194

Kepler’s Star 183, 285Keyser, Pietr Dirksz 40Khrushchev, Nikita

189–192, 268Khwarizmi, Abu al-

186–187Kiel, University of 160, 235Kiev Polytechnic Institute

189Kirchoff, Gustav Robert

66–67, 187, 187–189, 235Kisk, Esther Christine 136,

138–139Koehler, Johann Gottfried

52Kohlschütter, Arnold 6Komarov, Vladimir 191Königsberg, University of 23,

179–180, 187Königsberg Observatory 23,

45–47Königsstuhl Observatory

281–282Korolev, Sergei Pavlovich

189–192KT boundary 14Kuffner Observatory 257Kuiper, Gerard Peter 84–85,

192, 192–194, 237

L

Lacaille, Nicolas-Louis de 52Lacroix, Sylvestre 153Lagrange, Joseph-Louis

195–197, 196, 198–199,220

Laistre, Genevieve de 77Lalande, Joseph-Jérôme Le

Français de 4, 232Lalande Medal 74, 84, 154,

174, 266

Index 313

Lambert, Johann 50Lamont, Johann von 4Landis, Janet L. 13Lang, Fritz 62, 108, 223Laplace, Pierre-Simon,

marquis de 196, 197–200,198, 264

Lassell, William 3Lauritsen, Charles C. 118Lavoisier, Antoine-Laurent

de 79, 155, 199Leavitt, Henrietta Swan 32,

75, 200, 200–201Legion d’Honneur 119, 197,

199, 204, 212Leibniz, Gottfried Wilhelm

146, 220Leiden, University of 54,

193, 227, 254–255, 262Leiden Observatory 163,

180, 227, 263Leipzig, University of 56–57,

60, 162Leissner, Siri Dorotea 83Lemaître, Georges-Édouard

201–203Le Monnier, Renée 197Leningrad, University of

15–16, 127–128Leonids 5Leverrier, Urbain-Jean-

Joseph 2–4, 126–127, 203,203–204

Ley, Willy 63, 108, 223Libby, Willard 100Lick Observatory 35, 72–74,

73, 74, 84, 92–93, 93, 141,193, 216

Lieben Prize, Hess and 165light velocity 212–214, 217,

262light waves 21–22Lilienthal Observatory 45Lindbergh, Charles 139

Lindblad, Bertil 227Lippershey, Hans 205–206liquid propellant rockets

107, 109, 135, 138–139Lo, Fred 243Lockyer, Joseph Norman

206–208Lombroso, Nora 245London, University of 68longitude 77, 145–146, 187Los Alamos National

Laboratory. See ManhattanProject

Louis XIV (king of France)77, 204

Louis XV (king of France)212

Louis XVI (king of France)197, 199

Louis XVIII (king of France)199

Louvain, University of201–202

Lovell, Bernard 42Lowell, Percival 84, 99,

208–210, 253–254, 269Lowell Observatory 84, 99,

208–210, 265, 269–270Lunar and Planetary

Observatory 194lunar crater names

Arago 22Aristotle 27, 239Aryabhata 30Baade 34Beg 42Bessel 47Bode 53Cannon 76Cavendish 80Eddington 107Einstein 114Eudoxus 239Fleming 118

Halley 146Herschel (Caroline) 153Herschel (John) 156Herschel (William) 160Hubble 172Korolev 191Leavitt 201Plato 239

Lund, University of 83Lunik 3 191Luther, Martin 91

M

MacDonald Observatory 70Mach, Ernest 57, 112Maestlin, Michael 183Magellanic Premium Award,

American PhilosophicalSociety 12, 44

main sequence stars 163Malmquist, Karl 83Malvasia, Cornelio 76Ma’mun, al- (caliph of

Baghdad) 38, 186Manchester, University of

48, 106Manhattan Project 13, 49,

89, 245, 273Maragheh Observatory 41Marconi, Guglielmo 161Maric, Mileva 111, 114Mariner 4 209Marischal College 155Marius, Simon 32Mars

Barnard and 36Braun and 64Campbell and 74Cassini and 77Douglass and 99Hall and 142–143Kepler and 183–184

314 A to Z of Scientists in Space and Astronomy

Korolev and 192Kuiper and 193Lowell and 208–210Schiaparelli and 253–254

Marsburg, University of 67Martian crater names

Arago 22Halley 146Herschel 156

Maskelyne, Nevil 46, 158,233

Massachusetts Institute ofTechnology 13, 49, 141,202, 209, 233, 245–246

Mauna Kea Observatory 194Maury, Antonia 234Max (rocket) 62Maxwell, James Clerk 57,

79, 111, 132, 160–161, 188Maxwell-Boltzmann

distribution 57Mayer, Tobias 52Mazursky Award 252McCloskey, Betty 88McDonald Observatory 193Melanchthon 91Memorial Medal, Royal

Physiographic Society 83Mendeleev, Dmitri 67, 271Merck, Marie 235Mercury 194Messier, Charles 32, 158,

211–212Metius, Jacob 206Miami, University of 97Michell, John 149Michelson, Albert Abraham

141, 212–214, 213Michelson Medal 44, 168Michelson-Morley

experiment 213–214Michigan, University of 72,

92, 94, 142Milan, University of 129

Milikan, Robert 17, 165,170, 283

Milky Way Galaxy 31–32,53–55, 92–94, 159, 171,180–181, 226–227,259–261

Miller, Adeline L. 6Miller, Stanley 273–275Miller, W. Allen 172–173Milne, Edward A. 80Mimas 159Minkowski, Rudolf Leo

Bernhard 31, 34, 111–112Minnesota, University of 88Miranda 159, 192–194Missouri, University of 260Mitchell, Charlotte Tiffany

175–176Mitterrand, François 119Mocenigo, Zuane 65momentum 218Montana, University of 273Moon. See also lunar crater

namesAdams and 4–5Aryabhata and 30Bradley and 59Braun and 64Cassini and 77Draper and 102–103Ehricke and 109–110Euler and 115–116Galileo and 124Gill and 132Halley and 146Kant and 180Kepler and 185Korolev and 191–192Kuiper and 194Lagrange and 196Oberth and 221

Moore, Patrick 271Moritz (rocket) 62Morley, William 213–214

Morrison, Philip 101motion 26, 123, 182–186,

218–220Mount Palomar Observatory

171, 255, 285Mount Stromlo Observatory

34, 55Mount Wilson Observatory

5, 5, 6–7, 31–32, 34, 68–69,142, 171, 176, 214, 248,260–261

Mueller, Barbara 183–184Mullard Radio Astronomy

Laboratory 43–44, 167,250

Munich, University of 47,56, 160, 223, 235, 257

Munich Technical University168

Münster, University of 31Murray, Margaret Lindsay

172, 174

N

Napa College 92Napier, John 185Napoleon Bonaparte 45,

197–199, 212National Academy of Arts

and Sciences 96National Academy of

Sciences (U.S.). See alsoHenry Draper Medal;Public Welfare Medal;Watson Gold Medal

Adams and 7Anderson and 18Burbidge and 70Campbell and 74Curtis and 93Dirac and 96Draper and 103

Index 315

National Academy ofSciences (U.S.) (continued)

Fowler and 119Gamow and 129Hawking and 150Penzias and 232Rees and 244Rossi and 246Shapley and 261Wilson and 281

National Aeronautics andSpace Administration(NASA)

Alpher and 10Braun and 61, 64Chandrasekhar and 82Compton and 87–88and Einstein 131Giacconi and 130–131and Goddard 139Kuiper and 193–194Rossi and 244and Sagan 251–252and Van Allen 277–278

National Institute of Sciencesof India 96

National Medal of Science(U.S.) 15, 71, 82, 119,247

National Radio AstronomyObservatory (NRAO) 101,131, 242–243

Naval Observatory, U.S. 84,142–143, 215–216

Naval Research Laboratory130

Naysmyth, Alexander 263nebula hypothesis 176,

179–180, 197nebulas 37, 50, 52, 173,

211–212nebulium 173, 207Neddermey, Seth 18Néel, Louis 9

Neher, Victor 17Nell 139Neptune 1–5, 21, 53,

126–127, 155, 203–204Nereid 192–194neutron star hypothesis 285Newcomb, Simon 84,

215–217, 216New Mexico State University

270Newton, Isaac 83, 111,

144–146, 179, 182, 186,197–199, 217, 217–220,241

New York University 103Niepce, Nicéphor 21Nobel Institute 9, 28–29Nobel Prize laureatesAlfvén 8–9

Alvarez 12, 14–15Anderson 18Arrhenius 27–28Bethe 49Chandrasekhar 81Compton 88–89Dirac 96Einstein 113Fowler 119Giacconi 129Hess 165Hewish 166, 168Michelson 212, 214Penzias 229, 232Planck 236Raman 80–81Ryle 249–250Urey 273, 275Wilson 281

Norman Lockyer Observatory208

Northern Arizona University270

novas 33, 174Novikov, Igor 11

Novorossysky University 127nuclear weapons 96, 114.

See also Manhattan Project

nutation 58–59

O

Oberlin College 200Oberon 159Oberth, Hermann Julius 62,

108, 169, 221–224, 222occultation 144Ohio State University 118,

243Ohm, Georg Simon 187Olbers, Heinrich Wilhelm

Matthäus 44–47,224–226

Olbert, Stanislaw 246Olmsted, Ardiane Foy 119Oort, Jan Hendrik 226,

226–228, 254, 263Open University 44Öpik, Ernst 228Oppenheimer, Robert 49, 96,

149Oppenheimer Prize 44optics 20–21, 185, 212–214,

219–220, 241, 253Order of Lenin 268Order of Merit (British

honor) 97, 176Oriani, Barnabas 52Orion Nebula 102–103Oslander, Andreas 91Ostwald, Wilhelm 162Owens, Gladys Mary 177Owens College 106Owens Valley Radio

Observatory 280Oxford University 58, 76,

145–147, 170, 249

316 A to Z of Scientists in Space and Astronomy

P

Padua, University of 90, 124,245

Palermo Academy 47Palermo Observatory 233Palitzch, Georg 212Pallas 224Palmer, Anna Mary 103Palmer, Rowena 249panspermia hypothesis

27–29Panzano Observatory 76parallax 5–7, 46–47, 58, 77,

132–134Paris, University of 204Paris Academy (Académie

royale des sciences de Paris)115

Paris Observatory 2, 77–78,204

Parsbjerg, Manderup 60Pauli, Wolfgang 81Paul V (pope) 125Payne-Gaposchkin, Cecilia

Helena 248Peacock, George 153Pearman, J. Peter 101Pellepoix, Antoine Darquier

de 52Penrose, Roger 49, 147, 149Penzias, Arno Allen

229–232, 230, 280–281Perseids 254Phobos 84, 142–143photography 21, 35–37, 75,

102–103, 132, 154–155, 173photometry 21–22, 82Physical Engineering

Institute 97Physical Institute, Swedish

Academy of Sciences 28Physical Society 107Physics Museum, Munich 121

pi 30, 50Piazzi, Giuseppe 53,

232–233Picard, Jean 78Piccard, Auguste 283Pickering, Edward Charles

74–76, 117, 141, 200–201,209, 233–234, 234

Pickering, William Henry234, 278

Pigott, Edward 52Pike’s Peak experiment 18pi mesons 49Pisa, University of 122–124Pius VII (pope) 232Planck, Max Karl 193, 235,

235–237planetary motion 182–186,

197Planetary Society 252Plato 25, 183, 237–239Playfair, John 264Pleiades 82, 163Plutarch 24Pluto 53, 84, 208–210, 266,

268–271Poncelet Prize, Académie des

Sciences 87Pontifical Academy of

Sciences 96, 202, 244Potsdam Astrophysical

Observatory 163, 258Pound, James 58Prague, University of 98precession 39Presidential Certificate of

Merit 18Presidential Medal of Merit

119President’s Science Advisory

Committee 49Prime Mover 26primitive atom 202Princeton Observatory 248

Princeton University 44, 88,96, 114, 175, 231, 247, 249,258

Prix Francqui 202Procyon 47Project Ozma 101prominence 206Prony, Gaspard de 21Proxenus of Atarneus 25Prussian Academy of

Sciences 115Ptolemy, Claudius 8, 22,

38–39, 90–91, 125,186–187, 239–241

Public Welfare Medal,National Academy ofSciences 252

Pulitzer Prize 251Pulkovo Astronomical

Observatory 15–16, 23, 82,84, 254

pulsars 42–44, 165–168Pythagoras 183, 238Pythias 25

Q

quadrant 42quantum theory 95–97, 111,

113, 149, 236–237quasars 43, 70, 243–244,

254–255quasi-stellar object (QSO)

255Quistorp, Maria von 63

R

Radcliffe College 75, 200radio astronomy 43,

101–102, 165–168,242–243, 280–281

Index 317

Radiological Society of NorthAmerica 89

radio waves 160–161Raman, Chandrasekhara

Venkata 80–81Ramsay, William 79, 206Ranger Project 193–194Rayleigh, John William

Strutt 236Rayleigh-Jeans formula 236Reagan, Ronald 71Reber, Grote 242–243Rees, Eberhard 222Rees, Martin John 243,

243–244Regiomontanus, Johannes

240Reinhold, Erasmus 8Reinmuth, Karl Wilhelm 53relativity theory 106,

110–114, 147–149,257–258, 262

Reuttinger, Susanna 184Rhea 77Rheticus 91Rice University 280Rimpam, Adelheid 86rockets 61–64, 107–110,

134–139, 189–192,223–224, 271–272, 277

Roemer, Olaus 59Roentgen, Wilhelm 161Romanges, Marie-Charlotte

de Courty de 199Roope, P. M. 138Rosenberg, Peter Vok 61Rosenfeld, Léon 81Rossi, Bruno Benedetto

244–247, 245Rossi Prize 244Rostock, University of 60Royal Academy of Science of

Turin 195

Royal Academy of Sciencesof Uppsala 20

Royal Astronomical Society(Britain). See alsoEddington Medal; GoldMedal; Herschel Medal;Jackson-Gwilt Medal

Adams (John Crouch)and 5

Adams (Walter Sydney)and 7

Bell Burnell and 44Bessel and 47Chandrasekhar and 81Curtis and 94Eddington and 107Fleming and 118Fowler and 119Gill and 133Hale and 141Jeans and 176Rees and 244Secchi and 259Somerville and 264Wolf and 282

Royal College of Science207

Royal Danish Academy 97,129

Royal GreenwichObservatory 70, 104–106,144, 146, 160, 177–178

Royal Institute ofTechnology, Stockholm9–10

Royal Irish Academy 96,152, 264

Royal Medal, Royal Society82, 96, 107, 154–155, 174,178, 250

Royal Society of Edinburgh96

Royal Society (of London).See also Copley Medal;Davy Medal; HughesMedal; Royal Medal;Rumford Medal

Adams and 5Ångström and 20Bessel and 46Bunsen and 67Cavendish and 79–80Chandrasekhar and 80, 82Clausius and 87Dirac and 96Dyson and 104Eddington and 107Halley and 144–146Hawking and 150Herschel (Caroline) and

152Herschel (John) and

153–154Herschel (William) and

151, 158Hubble and 174Jeans and 175Jones and 178Kirchoff and 189Lagrange and 197Leverrier and 204Lockyer and 207–208Messier and 212Michelson and 214Newcomb and 217Newton and 219–220Rees and 244Ryle and 250Secchi and 259Somerville and 264

Royal Swedish Academy 20rubidium 68, 188Rudeck, Sofia 28Rudolf II (Holy Roman

Emperor) 61, 183–185

318 A to Z of Scientists in Space and Astronomy

Rumford Gold Medal,American Academy of Arts 89, 234, 247, 249,255, 261

Rumford Medal, RoyalSociety 20, 174, 208

Russell, Henry Norris162–163, 247, 247–249,260

Rutherford, Ernest 88, 128Ryle, Martin 165, 166, 167,

249–250

S

Sachs, Henry 138Sagan, Carl Edward 102,

251–252Sagan, Linda 102St. Helena Observatory 144St. Petersburg, University of.

See Leningrad, Universityof

St. Petersburg Academy ofSciences 115

Sandage, Alan 255Sappho 133satellites 185, 192Saturn 77–78, 126, 143, 159Saturn project 64Sawin, Elizabeth Rhoads 280Schaeberle, John 47Scheiner, Christoph

252–253Schiaparelli, Giovanni

Virginio 208–209,253–254

Schiff, Leonard I. 118Schmidt, Bernhard V. 31Schmidt, Maarten 254–256,

280Schönfeld, Eduard 23Schrödinger, Erwin 96

Schroter, Johann 45Schultz, Herman 82Schwabe, Samuel Heinrich

256–257Schwarzschild, Karl 6, 163,

257, 257–258Schwarzschild, Martin 258science fiction 62, 134, 185,

221Search for Extra-Terrestrial

Intelligence (SETI)101–102

Secchi, Pietro Angelo258–259

Shapley, Harlow 32–33,54–55, 92–94, 162, 248,259, 259–261, 260, 261

Shepard, Alan B., Jr. 191Sheppard, Scott S. 36Siding Spring Observatory

55Simba International

Women’s Movement Award268

Sirius 47, 173–174Sirius B 5–7, 84Sitter, Willem de 262–263Sitterly, Charlotte Emma

Moore 248Slee, Bruce 34Slipher, Vesto Melvin

209–210, 265, 265–266,269

Smithsonian Institution 137,139

Smithwick, Geraldine 13Sobel, Dava 102Société de Physique et

d’Histoire Naturelle deGenève 264

Society for CollegiateInstruction of Women 200

Socrates 237–238Sokolovaya, Varvara 271

Somerville, Mary Fairfax263–265

Somerville, William 264Sommerfeld, Arnold 47, 110,

113–114Sophist philosophers

237–238Southampton, University

43–44Soviet Academy of Sciences

16, 96, 272Soviet Cosmonauts

Federation, Sagan and 252Space Telescope Science

Institute 131space travel 61–64, 134, 136,

168–170, 189, 221–224,272

special theory of relativity112–113

spectrography 103spectroheliograph 141spectroscopy

Adams and 5–7Ångström and 19Bunsen and 66–68Campbell and 72, 74Cannon and 75Fraunhofer and 120–121Hale and 141Herschel and 154Huggins and 172–174Kirchoff and 187–189Kuiper and 193Lockyer and 206–208Secchi and 258–259Slipher and 266

spherical cosmology 26, 30,183, 238–239, 241

spiral galaxies 50, 53spiral nebulas 93, 265–266Sputnik project 63–64,

190–191, 272, 277Stack, Sophie 86

Index 319

Stalin, Joseph 190Stanley, G. 34Stefan, Josef 267Stefan-Boltzmann Law

55–57, 267stellar association 15–16stellar composition 106–107stellar energy 47–50, 56–57stellar evolution 161stellar motion 72, 146stellar nucleosynthesis 119stellar streaming 181Steward, Margaret Brodie 154Steward Observatory 54, 55,

99–100Stewart, John 248Stockholm, University of 281Stockholm Academy 47Stockholm Observatory 82Stockholm Technical

University 28Stoic philosophers 22Stonehenge 207–208Strasbourg, University of 257Strato of Lampsacus 24Stromberg, Gustav 83Strutt, John William 236Struve, Otto 81, 101,

253–254Struve, Friedrich Georg

Wilhelm von 15, 23Stuhlinger, Ernst 222Stuttgart, University of 47Sufi, Abd-al-Rahman al- 32Sun

Ångström and 19–20Herschel and 155, 159Lockyer and 206Secchi and 259

sunspotsAlfvén and 8Ambartsumian and 15Douglass and 99–100Galileo and 125

Scheiner and 252Schwabe and 256

superclusters 261supergiant stars 248supernovas 33, 60, 124, 183,

283, 285Surveyor Project 193–194Sussex University 244Swedish Academy of

Sciences 28–29, 201. Seealso Nobel Prize laureates;Physical Institute

Swift, Jonathan 143

T

Talbot, William Henry Fox155

Tamm, Igor 96Tebbutt’s comet 103telescopes

Baade and 34Barnard and 35–36Clark and 83–85Galileo and 124–125Hale and 140Herschels and 151, 157,

159–160Hewish and 167Huggins and 172Kepler and 185Kuiper and 193Lippershey and 205–206Newton and 219Ryle and 250Schwabe and 256Tombaugh and 269

Teller, Edward 49, 128Temple University 18Tereshkova, Valentina 268test particles 202Thackeray, William G. 104

Thales 237thermodynamics, laws of

85–86, 147Thetys 77Thomas, Robert Baily 151Thomas Aquinas 26Throop Polytechnic Institute.

See California Institute ofTechnology

Tikhov, Gavriil Adrianovich84

time travel 147, 149Titan 192–193Titania 159Titius, Johann 51Titov, Gherman 268Toftoy, H. N. 222Tombaugh, Clyde William

84, 208, 210, 266, 268–271Tooke, Mary 144Townes, Charles 229–230Trojan asteroid group

281–282Truman, Harry S. 119Tsiolkovsky, Konstantin

Eduardovich 189, 223,271–272

Tübingen University 48, 183Tupolev, Andrey 189Turin, College of 195Turin, University of 253Turku Observatory 23Turner, Herbert Hall

117–118Tusi, Nasir al-Din 41, 240Tycho’s Star 33, 285

U

Uhuru satellite 131Umbriel 159Union College 12

320 A to Z of Scientists in Space and Astronomy

United Nations Gold Medalof Peace 268

universe expansion, Hubbleand 172–174

universe size, Curtis and92–94

University College, London44, 79

University Observatory 162Uppsala, University of 8,

19–20, 27–28, 82Uppsala Observatory 19, 82Urania Observatory 162Uranus 1–3, 151, 158–159,

204Urban VIII (pope) 125Urey, Harold Clayton

273–275, 274Urey-Miller experiment

273–275Utrecht, University of 180

V

Valz Prize 174Van Allen, Abigail 276Van Allen, James Alfred

276–279, 278Vanderbilt University 37Vanguard project 64, 277Venus 7Verein für Raumschiffahrt

(VFR) 62, 108, 169–170,223–224

Verne, Jules 62, 134, 221Vesta 224Victoria (asteroid) 133Victoria Gold Medal, Royal

Geographical Society 265Victoria (queen of Great

Britain, empress of India)5, 172, 174, 208

Vienna, Physical Institute of267

Vienna, Technical Universityof 224

Vienna, University of 56–57,98, 267

Vienna Polytechnic Institute97–98

Viennese Academy ofSciences 164–165, 267

Virginia, University of 93Vitruvius 24Vogel, Hermann 234Voskhod project 191–192Vostok project 191, 268Vulcan 204, 256

W

Wallace, William 264Wallenstein, Albrecht von

183–184Ward, Effie 138Warner, H. H. 35Washington University

88–89Watson, James 129Watson, William 158Watson Gold Medal,

National Academy ofSciences 83, 134, 182, 263

Wellesley College 75, 118Wells, H. G. 62, 134Westminster Abbey 5, 156Wexler, Marcus 252Wheeler, John 149white dwarves 7, 47, 80, 84,

118, 248Wickham, Lillian 6Wigner, Eugene 96Wigner, Margit 96Wilde, Jane 147, 150

Willard Gibbs Medal,American ChemicalSociety 29

William Herschel Museum152–153, 159

William III (king of GreatBritain) 145, 220

William the Silent (prince ofOrange) 205

Wilson, Charles 88Wilson, Robert Woodrow

229–232, 230, 280–281Wisconsin, University of 103Wittenberg, University of 60Wolf, Johann Rudolf 257Wolf, Maximilian 281–282Wolff, Christian 51Wollaston, William H. 120Woltosz, Walt 147women in astronomy and

space scienceBurbidge 68–71Cannon 74–76Fleming 117–118Herschel 150–153Leavitt 200–201Somerville 263–265Tereshkova 268

Wooley, Richard van der Riet105

Wooster College 87Worcester Polytechnic

Institute 136worm holes 147, 149Würzberg, University of

86–87

X

X-ray astronomy 129–132,244, 246

X-rays 87–89, 161

Index 321

Y

Yale University 226year length 30, 38–39, 42, 241Yegorov, Boris 191Yerevan State University 16Yerkes, Charles Tyson 141Yerkes Observatory 6, 36–37,

68, 70, 81, 84–85, 141–142,170, 193

ylem 10, 128Young, Thomas 20

Z

Zarqali, Abu Ishaq IbrahimIbm Yahya al- 8

Zhang Sui 146Zöllner, Karl Friedrich 21–22

Zurich, University of111–112

Zurich Polytechnic Institute111

Zwicky, Fritz 31–32, 49,283–285, 284

322 A to Z of Scientists in Space and Astronomy